XML 163 R93.htm IDEA: XBRL DOCUMENT v3.6.0.2
Reserves for Unpaid Losses and Loss Adjustment Expenses Level 4 Historical Loss Development Triangles, P&C (Details)
number in Millions, $ in Millions
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Dec. 31, 2012
USD ($)
Dec. 31, 2011
USD ($)
Dec. 31, 2010
USD ($)
Dec. 31, 2009
USD ($)
Dec. 31, 2008
USD ($)
Dec. 31, 2007
USD ($)
General Liability [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 3,546                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,981                  
General Liability [Member] | Short-duration Insurance Contracts, Accident Year 2007 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net 416 $ 415 $ 416 $ 428 $ 461 $ 489 $ 491 $ 524 $ 570 $ 601
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 362 355 347 335 315 289 230 161 94 46
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (46)                  
Short-duration Insurance Contracts, Number of Reported Claims 23,384                  
General Liability [Member] | Short-duration Insurance Contracts, Accident Year 2008 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 398 401 398 416 451 454 468 457 501  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 337 330 318 300 270 216 141 69 31  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (50)                  
Short-duration Insurance Contracts, Number of Reported Claims 21,181                  
General Liability [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 346 347 348 359 382 394 398 382    
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 287 277 256 227 181 124 63 22    
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (46)                  
Short-duration Insurance Contracts, Number of Reported Claims 20,268                  
General Liability [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 376 345 343 355 352 362 355      
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 314 259 224 181 115 51 14      
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (43)                  
Short-duration Insurance Contracts, Number of Reported Claims 18,482                  
General Liability [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 320 315 316 323 343 353        
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 234 198 154 93 47 11        
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (55)                  
Short-duration Insurance Contracts, Number of Reported Claims 16,344                  
General Liability [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 304 295 310 315 321          
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 167 124 75 39 8          
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (93)                  
Short-duration Insurance Contracts, Number of Reported Claims 11,230                  
General Liability [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 352 332 321 318            
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 152 95 35 7            
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (145)                  
Short-duration Insurance Contracts, Number of Reported Claims 9,211                  
General Liability [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 336 318 317              
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 88 31 11              
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (180)                  
Short-duration Insurance Contracts, Number of Reported Claims 9,366                  
General Liability [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 346 316                
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 32 7                
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (260)                  
Short-duration Insurance Contracts, Number of Reported Claims 9,246                  
General Liability [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 352                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 8                  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (323)                  
Short-duration Insurance Contracts, Number of Reported Claims 8,463                  
Package Business [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 6,469                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 5,214                  
Package Business [Member] | Short-duration Insurance Contracts, Accident Year 2007 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net 586 0 592 592 600 600 621 638 626 575
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 565 0 559 552 542 525 484 432 362 223
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (17)                  
Short-duration Insurance Contracts, Number of Reported Claims 53,645                  
Package Business [Member] | Short-duration Insurance Contracts, Accident Year 2008 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 675 0 676 674 675 677 709 703 667  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 649 0 633 620 595 562 510 451 278  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (19)                  
Short-duration Insurance Contracts, Number of Reported Claims 58,028                  
Package Business [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 576 0 577 578 572 584 584 587    
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 547 0 527 503 463 411 351 227    
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (25)                  
Short-duration Insurance Contracts, Number of Reported Claims 50,263                  
Package Business [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 653 0 652 652 654 662 657      
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 613 0 570 539 487 414 270      
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (29)                  
Short-duration Insurance Contracts, Number of Reported Claims 52,259                  
Package Business [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 814 0 800 790 792 810        
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 748 0 684 621 555 377        
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (44)                  
Short-duration Insurance Contracts, Number of Reported Claims 60,793                  
Package Business [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 736 0 728 725 736          
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 652 0 560 486 286          
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (55)                  
Short-duration Insurance Contracts, Number of Reported Claims 59,472                  
Package Business [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 585 0 565 579            
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 467 0 339 225            
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (66)                  
Short-duration Insurance Contracts, Number of Reported Claims 43,077                  
Package Business [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 601 0 566              
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 416 0 226              
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (118)                  
Short-duration Insurance Contracts, Number of Reported Claims 42,230                  
Package Business [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 588 0                
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 332 0                
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (185)                  
Short-duration Insurance Contracts, Number of Reported Claims 40,140                  
Package Business [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 655                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 225                  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (314)                  
Short-duration Insurance Contracts, Number of Reported Claims 36,845                  
Commercial Property [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 3,041                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 2,870                  
Commercial Property [Member] | Short-duration Insurance Contracts, Accident Year 2007 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net 296 296 296 295 295 294 295 299 306 306
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 297 296 296 295 294 293 293 291 277 185
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (1)                  
Short-duration Insurance Contracts, Number of Reported Claims 32,589                  
Commercial Property [Member] | Short-duration Insurance Contracts, Accident Year 2008 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 464 463 464 464 467 464 465 465 478  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 466 465 464 464 464 459 449 422 280  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ 0                  
Short-duration Insurance Contracts, Number of Reported Claims 31,995                  
Commercial Property [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 257 257 257 251 258 259 264 267    
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 257 257 257 256 256 252 247 179    
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ 0                  
Short-duration Insurance Contracts, Number of Reported Claims 28,284                  
Commercial Property [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 284 284 284 282 279 283 286      
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 284 284 283 281 276 266 198      
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ 0                  
Short-duration Insurance Contracts, Number of Reported Claims 28,513                  
Commercial Property [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 360 361 362 356 356 357        
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 359 358 355 350 332 231        
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ 0                  
Short-duration Insurance Contracts, Number of Reported Claims 29,099                  
Commercial Property [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 306 305 301 301 329          
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 304 300 294 279 171          
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (1)                  
Short-duration Insurance Contracts, Number of Reported Claims 25,777                  
Commercial Property [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 220 219 218 234            
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 218 216 208 157            
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ 0                  
Short-duration Insurance Contracts, Number of Reported Claims 20,280                  
Commercial Property [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 262 260 268              
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 258 243 168              
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ 0                  
Short-duration Insurance Contracts, Number of Reported Claims 19,720                  
Commercial Property [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 264 264                
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 239 172                
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (3)                  
Short-duration Insurance Contracts, Number of Reported Claims 18,955                  
Commercial Property [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 328                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 188                  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (48)                  
Short-duration Insurance Contracts, Number of Reported Claims 18,189                  
Commercial Auto Liability [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 3,438                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 2,594                  
Commercial Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2007 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net 355 353 351 350 350 351 352 351 333 334
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 349 348 347 343 334 322 292 227 153 68
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (1)                  
Short-duration Insurance Contracts, Number of Reported Claims 50,392                  
Commercial Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2008 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 306 307 302 304 304 303 304 311 303  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 300 299 295 289 270 238 185 124 61  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (4)                  
Short-duration Insurance Contracts, Number of Reported Claims 43,859                  
Commercial Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 302 302 301 297 287 287 292 306    
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 300 298 291 274 237 175 115 56    
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (1)                  
Short-duration Insurance Contracts, Number of Reported Claims 38,651                  
Commercial Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 327 328 323 319 296 280 277      
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 308 300 289 252 188 125 55      
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (11)                  
Short-duration Insurance Contracts, Number of Reported Claims 38,007                  
Commercial Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 365 366 356 356 310 272        
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 339 315 273 211 133 62        
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (12)                  
Short-duration Insurance Contracts, Number of Reported Claims 39,093                  
Commercial Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 394 401 390 376 311          
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 345 306 233 142 65          
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (26)                  
Short-duration Insurance Contracts, Number of Reported Claims 35,719                  
Commercial Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 336 329 314 309            
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 255 199 128 61            
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (40)                  
Short-duration Insurance Contracts, Number of Reported Claims 31,510                  
Commercial Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 328 314 306              
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 195 129 58              
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (71)                  
Short-duration Insurance Contracts, Number of Reported Claims 28,742                  
Commercial Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 353 302                
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 141 61                
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (140)                  
Short-duration Insurance Contracts, Number of Reported Claims 27,205                  
Commercial Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 372                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 62                  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (251)                  
Short-duration Insurance Contracts, Number of Reported Claims 24,553                  
Commercial Auto Physical Damage [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 227                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 219                  
Commercial Auto Physical Damage [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net 73 73 72              
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 73 73 67              
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ 0                  
Short-duration Insurance Contracts, Number of Reported Claims 31,724                  
Commercial Auto Physical Damage [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 75 74                
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 75 69                
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ 0                  
Short-duration Insurance Contracts, Number of Reported Claims 26,761                  
Commercial Auto Physical Damage [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 79                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 71                  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (1)                  
Short-duration Insurance Contracts, Number of Reported Claims 24,826                  
Professional Liability [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,761                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,225                  
Professional Liability [Member] | Short-duration Insurance Contracts, Accident Year 2007 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net 220 210 210 210 212 201 203 237 274 275
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 200 191 190 187 178 142 117 85 53 11
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (14)                  
Short-duration Insurance Contracts, Number of Reported Claims 4,182                  
Professional Liability [Member] | Short-duration Insurance Contracts, Accident Year 2008 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 277 282 276 276 280 274 244 253 281  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 264 260 230 221 202 166 126 61 13  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (10)                  
Short-duration Insurance Contracts, Number of Reported Claims 4,956                  
Professional Liability [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 257 255 263 257 266 244 251 254    
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 226 225 226 194 177 127 69 17    
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (19)                  
Short-duration Insurance Contracts, Number of Reported Claims 5,113                  
Professional Liability [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 195 200 201 205 212 211 202      
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 162 157 148 137 103 62 22      
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (30)                  
Short-duration Insurance Contracts, Number of Reported Claims 4,888                  
Professional Liability [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 219 219 226 232 228 226        
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 170 163 128 100 57 11        
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (42)                  
Short-duration Insurance Contracts, Number of Reported Claims 4,702                  
Professional Liability [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 146 149 168 172 174          
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 97 89 60 41 11          
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (45)                  
Short-duration Insurance Contracts, Number of Reported Claims 3,716                  
Professional Liability [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 110 123 136 136            
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 39 31 19 4            
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (66)                  
Short-duration Insurance Contracts, Number of Reported Claims 2,771                  
Professional Liability [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 118 123 116              
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 40 21 4              
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (65)                  
Short-duration Insurance Contracts, Number of Reported Claims 2,857                  
Professional Liability [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 113 104                
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 23 4                
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (75)                  
Short-duration Insurance Contracts, Number of Reported Claims 2,898                  
Professional Liability [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 106                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 4                  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (94)                  
Short-duration Insurance Contracts, Number of Reported Claims 2,709                  
Surety Product Line [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 657                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 444                  
Surety Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2007 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net 135 132 129 106 109 101 105 104 76 76
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 132 131 129 111 104 68 42 38 29 8
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (3)                  
Short-duration Insurance Contracts, Number of Reported Claims 5,387                  
Surety Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2008 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 48 47 44 47 47 52 62 67 75  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 39 39 39 34 32 30 23 18 5  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (7)                  
Short-duration Insurance Contracts, Number of Reported Claims 3,443                  
Surety Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 49 49 51 57 58 69 71 71    
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 44 44 43 44 46 45 32 9    
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (4)                  
Short-duration Insurance Contracts, Number of Reported Claims 3,301                  
Surety Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 70 69 73 79 80 75 71      
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 66 63 59 58 59 46 13      
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ 0                  
Short-duration Insurance Contracts, Number of Reported Claims 2,659                  
Surety Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 70 70 75 76 76 72        
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 59 57 56 51 39 12        
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (11)                  
Short-duration Insurance Contracts, Number of Reported Claims 2,118                  
Surety Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 48 53 60 69 69          
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 25 24 26 25 12          
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (19)                  
Short-duration Insurance Contracts, Number of Reported Claims 1,712                  
Surety Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 48 54 58 63            
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 18 17 9 3            
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (29)                  
Short-duration Insurance Contracts, Number of Reported Claims 1,437                  
Surety Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 65 65 69              
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 40 31 18              
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (23)                  
Short-duration Insurance Contracts, Number of Reported Claims 1,347                  
Surety Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 65 65                
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 19 9                
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (39)                  
Short-duration Insurance Contracts, Number of Reported Claims 1,294                  
Surety Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 59                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 2                  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (52)                  
Short-duration Insurance Contracts, Number of Reported Claims 1,082                  
Personal Auto Liability [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 12,304                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 10,703                  
Personal Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2007 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net 1,209 1,211 1,211 1,215 1,216 1,219 1,229 1,242 1,260 1,291
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,206 1,205 1,204 1,200 1,191 1,175 1,129 1,037 846 452
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (2)                  
Short-duration Insurance Contracts, Number of Reported Claims 260,143                  
Personal Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2008 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,188 1,191 1,192 1,196 1,197 1,207 1,227 1,249 1,253  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,184 1,183 1,181 1,175 1,160 1,121 1,031 861 469  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (2)                  
Short-duration Insurance Contracts, Number of Reported Claims 248,987                  
Personal Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,257 1,259 1,260 1,256 1,255 1,280 1,305 1,351    
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,250 1,246 1,240 1,223 1,171 1,083 888 492    
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (2)                  
Short-duration Insurance Contracts, Number of Reported Claims 254,543                  
Personal Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,265 1,275 1,282 1,287 1,293 1,321 1,346      
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,256 1,251 1,239 1,202 1,108 915 496      
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (4)                  
Short-duration Insurance Contracts, Number of Reported Claims 248,940                  
Personal Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,154 1,166 1,173 1,180 1,170 1,181        
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,140 1,126 1,088 1,006 826 447        
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (9)                  
Short-duration Insurance Contracts, Number of Reported Claims 221,862                  
Personal Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,133 1,142 1,146 1,149 1,141          
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,104 1,067 986 818 441          
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (14)                  
Short-duration Insurance Contracts, Number of Reported Claims 210,715                  
Personal Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,153 1,144 1,145 1,131            
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,091 1,002 816 442            
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (23)                  
Short-duration Insurance Contracts, Number of Reported Claims 205,308                  
Personal Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,198 1,153 1,146              
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,032 843 430              
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (72)                  
Short-duration Insurance Contracts, Number of Reported Claims 208,364                  
Personal Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,340 1,195                
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 935 475                
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (206)                  
Short-duration Insurance Contracts, Number of Reported Claims 214,436                  
Personal Auto Liability [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,407                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 505                  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (571)                  
Short-duration Insurance Contracts, Number of Reported Claims 201,606                  
Personal Auto Physical Damage [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,908                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,876                  
Personal Auto Physical Damage [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net 611 612 614              
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 612 613 591              
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ 0                  
Short-duration Insurance Contracts, Number of Reported Claims 392,193                  
Personal Auto Physical Damage [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 632 629                
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 630 610                
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ 0                  
Short-duration Insurance Contracts, Number of Reported Claims 395,384                  
Personal Auto Physical Damage [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 665                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 634                  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (3)                  
Short-duration Insurance Contracts, Number of Reported Claims 383,870                  
Homeowners [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 7,323                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 7,024                  
Homeowners [Member] | Short-duration Insurance Contracts, Accident Year 2007 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net 580 580 580 580 581 582 581 581 590 578
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 579 578 578 576 575 572 569 557 537 402
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (1)                  
Short-duration Insurance Contracts, Number of Reported Claims 133,741                  
Homeowners [Member] | Short-duration Insurance Contracts, Accident Year 2008 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 780 779 779 779 779 778 777 768 742  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 778 777 777 775 773 764 750 721 548  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (2)                  
Short-duration Insurance Contracts, Number of Reported Claims 165,101                  
Homeowners [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 769 772 772 772 772 776 777 757    
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 766 766 765 763 759 749 727 559    
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (2)                  
Short-duration Insurance Contracts, Number of Reported Claims 149,783                  
Homeowners [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 836 840 840 840 838 850 838      
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 833 832 829 825 815 789 599      
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (2)                  
Short-duration Insurance Contracts, Number of Reported Claims 161,559                  
Homeowners [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 911 914 916 919 920 955        
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 905 903 899 891 871 709        
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (4)                  
Short-duration Insurance Contracts, Number of Reported Claims 179,353                  
Homeowners [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 739 741 741 741 774          
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 731 727 719 696 547          
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (4)                  
Short-duration Insurance Contracts, Number of Reported Claims 142,756                  
Homeowners [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 634 637 638 673            
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 622 611 590 467            
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (6)                  
Short-duration Insurance Contracts, Number of Reported Claims 113,399                  
Homeowners [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 702 707 710              
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 684 663 526              
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (9)                  
Short-duration Insurance Contracts, Number of Reported Claims 121,619                  
Homeowners [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 703 690                
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 645 487                
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (20)                  
Short-duration Insurance Contracts, Number of Reported Claims 119,097                  
Homeowners [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 669                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 481                  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (84)                  
Short-duration Insurance Contracts, Number of Reported Claims 111,072                  
Property and Casualty, Commercial Insurance Product Line [Member] | Accident and Health Insurance Product Line [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 17,948                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 10,775                  
Property and Casualty, Commercial Insurance Product Line [Member] | Accident and Health Insurance Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2007 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net 1,374 0 1,374 1,375 1,394 1,404 1,434 1,492 1,538 1,597
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,141 1,122 1,094 1,053 1,000 935 845 727 547 $ 239
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (114)                  
Short-duration Insurance Contracts, Number of Reported Claims 148,662                  
Property and Casualty, Commercial Insurance Product Line [Member] | Accident and Health Insurance Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2008 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,493 0 1,477 1,477 1,473 1,470 1,456 1,444 1,456  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,216 1,190 1,146 1,089 1,015 917 781 581 $ 264  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (129)                  
Short-duration Insurance Contracts, Number of Reported Claims 141,632                  
Property and Casualty, Commercial Insurance Product Line [Member] | Accident and Health Insurance Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,529 0 1,504 1,504 1,493 1,478 1,455 1,462    
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,208 1,170 1,115 1,042 937 792 587 $ 265    
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (182)                  
Short-duration Insurance Contracts, Number of Reported Claims 135,757                  
Property and Casualty, Commercial Insurance Product Line [Member] | Accident and Health Insurance Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,881 0 1,857 1,858 1,814 1,775 1,560      
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,439 1,374 1,287 1,154 970 709 $ 316      
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (267)                  
Short-duration Insurance Contracts, Number of Reported Claims 156,400                  
Property and Casualty, Commercial Insurance Product Line [Member] | Accident and Health Insurance Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 2,224 0 2,206 2,204 2,099 2,013        
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,622 1,518 1,368 1,156 841 $ 371        
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (402)                  
Short-duration Insurance Contracts, Number of Reported Claims 177,279                  
Property and Casualty, Commercial Insurance Product Line [Member] | Accident and Health Insurance Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 2,168 0 2,207 2,207 2,185          
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,436 1,313 1,106 809 $ 359          
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (512)                  
Short-duration Insurance Contracts, Number of Reported Claims 170,535                  
Property and Casualty, Commercial Insurance Product Line [Member] | Accident and Health Insurance Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,883 0 1,981 2,020            
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 1,071 917 675 $ 304            
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (596)                  
Short-duration Insurance Contracts, Number of Reported Claims 147,997                  
Property and Casualty, Commercial Insurance Product Line [Member] | Accident and Health Insurance Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,789 0 1,869              
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 811 598 $ 275              
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (761)                  
Short-duration Insurance Contracts, Number of Reported Claims 123,794                  
Property and Casualty, Commercial Insurance Product Line [Member] | Accident and Health Insurance Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,835 0                
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 576 $ 261                
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (1,012)                  
Short-duration Insurance Contracts, Number of Reported Claims 110,894                  
Property and Casualty, Commercial Insurance Product Line [Member] | Accident and Health Insurance Product Line [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member]                    
Claims Development [Line Items]                    
Short-duration Insurance Contracts, Incurred Claims and Allocated Claim Adjustment Expense, Net $ 1,772                  
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net 255                  
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net $ (1,256)                  
Short-duration Insurance Contracts, Number of Reported Claims 98,070