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v3.10.0.1

Segment Information (Revenue by Segment) (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | $ 604,836 | $ 568,030 | $ 1,196,664 | $ 1,128,884
Other income | 3,179 | 3,291 | 5,358 | 6,532
Net investment income | 45,553 | 41,430 | 88,784 | 78,849
Net realized and unrealized investment (losses) gains | (1,652) | 1,734 | (12,201) | 689
Total investment revenues | 43,901 | 43,164 | 76,583 | 79,538
Total revenues | 651,916 | 614,485 | 1,278,605 | 1,214,954
Standard Commercial Lines [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 478,894 | 446,610 | 946,084 | 887,884
Other income | 2,882 | 3,016 | 4,708 | 5,876
Standard Commercial Lines [Member] | Commercial Automobile [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 122,104 | 108,316 | 240,335 | 215,445
Standard Commercial Lines [Member] | Workers Compensation [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 80,021 | 79,460 | 158,844 | 158,786
Standard Commercial Lines [Member] | General Liability [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 153,002 | 141,503 | 302,831 | 281,487
Standard Commercial Lines [Member] | Commercial Property [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 82,162 | 78,052 | 162,488 | 154,443
Standard Commercial Lines [Member] | Business Owners' Policies [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 25,829 | 24,989 | 51,420 | 49,834
Standard Commercial Lines [Member] | Bonds Segment [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 8,335 | 6,986 | 16,469 | 13,484
Standard Commercial Lines [Member] | Other Commercial [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 4,559 | 4,288 | 8,989 | 8,529
Standard Personal Lines [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 75,974 | 71,947 | 150,582 | 143,529
Other income | 297 | 275 | 649 | 656
Standard Personal Lines [Member] | Personal Automobile [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 41,810 | 37,663 | 82,252 | 74,613
Standard Personal Lines [Member] | Homeowners [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 32,223 | 32,467 | 64,424 | 65,167
Standard Personal Lines [Member] | Other Personal [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 1,644 | 1,542 | 3,257 | 3,093
Excess And Surplus Operations [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 53,147 | 52,764 | 105,356 | 104,003
Other income | 0 | 0 | 1 | 0
Excess And Surplus Operations [Member] | General Liability [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 39,379 | 39,054 | 77,919 | 76,966
Excess And Surplus Operations [Member] | Commercial Property [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | $ 13,768 | $ 13,710 | $ 27,436 | $ 27,037

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