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v3.6.0.2

Segment Information (Revenue From Continuing Operations by Segment) (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2016 | Sep. 30, 2016 | Jun. 30, 2016 | Mar. 31, 2016 | Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned | $ 552,753 | $ 542,429 | $ 531,932 | $ 522,458 | $ 516,087 | $ 507,390 | $ 490,309 | $ 476,123 | $ 2,149,572 | $ 1,989,909 | $ 1,852,609
Other income |  |  |  |  |  |  |  |  | 8,881 | 7,456 | 16,945
Net investment income | $ 35,428 | $ 33,375 | $ 31,182 | $ 30,769 | $ 30,108 | $ 32,061 | $ 32,230 | $ 26,917 | 130,754 | 121,316 | 138,708
Realized investment (losses) gains |  |  |  |  |  |  |  |  | (4,937) | 13,171 | 26,599
Total investment revenues |  |  |  |  |  |  |  |  | 125,817 | 134,487 | 165,307
Total all segments |  |  |  |  |  |  |  |  | 2,284,270 | 2,131,852 | 2,034,514
Total revenues |  |  |  |  |  |  |  |  | 2,284,270 | 2,131,852 | 2,034,861
Miscellaneous Income [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Other income |  |  |  |  |  |  |  |  | 8,881 | 7,456 | 16,598
Other Income [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Other income |  |  |  |  |  |  |  |  | 0 | 0 | 347
Standard Commercial Lines [Member] | Commercial Automobile [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 398,942 | 358,909 | 333,310
Standard Commercial Lines [Member] | Workers Compensation [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 308,233 | 290,075 | 274,585
Standard Commercial Lines [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 527,859 | 483,291 | 444,938
Standard Commercial Lines [Member] | Commercial Property [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 293,438 | 269,022 | 244,792
Standard Commercial Lines [Member] | Business Owners' Policies [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 97,754 | 93,428 | 85,788
Standard Commercial Lines [Member] | Bonds Segment [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 23,227 | 20,350 | 19,288
Standard Commercial Lines [Member] | Other Commercial [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 16,030 | 14,367 | 13,011
Standard Commercial Lines [Member] | Miscellaneous Income [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 7,782 | 6,343 | 14,747
Standard Commercial Lines [Member] | Total standard Commercial Lines [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 1,673,265 | 1,535,785 | 1,430,459
Standard Personal Lines [Member] | Miscellaneous Income [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 1,098 | 1,113 | 1,834
Standard Personal Lines [Member] | Personal Automobile [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 142,876 | 146,784 | 151,317
Standard Personal Lines [Member] | Homeowners [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 130,973 | 134,382 | 134,273
Standard Personal Lines [Member] | Other Personal [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 6,758 | 6,968 | 11,157
Standard Personal Lines [Member] | Standard Personal Lines [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 281,705 | 289,247 | 298,581
E&S Lines [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 151,638 | 126,064 | 99,086
E&S Lines [Member] | Commercial Property [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | 51,844 | 46,269 | 41,064
E&S Lines [Member] | Miscellaneous Income [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Other income |  |  |  |  |  |  |  |  | 1 | 0 | 17
E&S Lines [Member] | Total standard Commercial Lines [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net premiums earned |  |  |  |  |  |  |  |  | $ 203,483 | $ 172,333 | $ 140,167

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