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Schedule III - Supplementary Insurance Information (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Deferred policy acquisition costs | $ 213,159 | $ 185,608 | $ 172,981
Reserve for loss and loss expenses | 3,517,728 | 3,477,870 | 3,349,770
Unearned premiums | 1,169,710 | 1,095,819 | 1,059,155
Net premiums earned | 1,989,909 | 1,852,609 | 1,736,072
Net investment income | 134,487 | 165,307 | 155,375
Losses and loss expenses incurred | 1,148,541 | 1,157,501 | 1,121,738
Amortization of deferred policy acquisition costs | 399,435 | 364,295 | 331,828
Other operating expenses | 292,904 | 252,670 | 243,740
Net premiums written | 2,069,904 | 1,885,280 | 1,810,159
Policy acquisition costs | 689,820 | 624,470 | 579,977
Other income | (7,456) | (16,945) | (12,294)
Other expenses | 38,371 | 32,696 | 31,863
Total | 692,339 | 616,965 | 575,568
Standard Commercial Lines [Member] |  |  |
Deferred policy acquisition costs | 171,476 | 147,285 | 138,397
Reserve for loss and loss expenses | 2,998,749 | 3,000,796 | 2,877,087
Unearned premiums | 803,648 | 734,697 | 708,861
Net premiums earned | 1,529,442 | 1,415,712 | 1,316,619
Net investment income | 0 | 0 | 0
Losses and loss expenses incurred | 819,573 | 870,018 | 831,261
Amortization of deferred policy acquisition costs | 323,753 | 295,774 | 270,443
Other operating expenses | 221,620 | 188,699 | 181,059
Net premiums written | 1,596,965 | 1,441,047 | 1,380,740
Standard Personal Lines [Member] |  |  |
Deferred policy acquisition costs | 17,258 | 17,495 | 18,149
Reserve for loss and loss expenses | 265,054 | 279,761 | 312,411
Unearned premiums | 276,533 | 285,777 | 286,969
Net premiums earned | 288,134 | 296,747 | 294,332
Net investment income | 0 | 0 | 0
Losses and loss expenses incurred | 200,237 | 197,182 | 206,450
Amortization of deferred policy acquisition costs | 33,638 | 34,851 | 33,097
Other operating expenses | 52,923 | 48,178 | 46,140
Net premiums written | 283,926 | 292,061 | 297,757
Excess And Surplus Operations [Member] |  |  |
Deferred policy acquisition costs | 24,425 | 20,828 | 16,435
Reserve for loss and loss expenses | 253,925 | 197,313 | 160,272
Unearned premiums | 89,529 | 75,345 | 63,325
Net premiums earned | 172,333 | 140,150 | 125,121
Net investment income | 0 | 0 | 0
Losses and loss expenses incurred | 128,731 | 90,301 | 84,027
Amortization of deferred policy acquisition costs | 42,044 | 33,670 | 28,288
Other operating expenses | 18,361 | 15,793 | 16,541
Net premiums written | 189,013 | 152,172 | 131,662
Investments Segment [Member] |  |  |
Deferred policy acquisition costs | 0 | 0 | 0
Reserve for loss and loss expenses | 0 | 0 | 0
Unearned premiums | 0 | 0 | 0
Net premiums earned | 0 | 0 | 0
Net investment income | 134,487 | 165,307 | 155,375
Losses and loss expenses incurred | 0 | 0 | 0
Amortization of deferred policy acquisition costs | 0 | 0 | 0
Other operating expenses | 0 | 0 | 0
Net premiums written | 0 | 0 | 0
Miscellaneous Income [Member] |  |  |
Other income | (7,456) | (16,598) | (12,201)
Other Income [Member] |  |  |
Other income | 0 | (347) | (93)
Miscellaneous Expense [Member] |  |  |
Other expenses | 9,975 | 9,093 | 7,792
Other Expense [Member] |  |  |
Other expenses | $ 28,396 | $ 23,603 | $ 24,071

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