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v3.7.0.1

Segment Information (Revenue by Segment) (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2017 | Jun. 30, 2016 | Jun. 30, 2017 | Jun. 30, 2016
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | $ 568,030 | $ 531,932 | $ 1,128,884 | $ 1,054,390
Net investment income | 41,430 | 31,182 | 78,849 | 61,951
Net realized investment gains (losses) | 1,734 | 1,765 | 689 | (939)
Total investment revenues | 43,164 | 32,947 | 79,538 | 61,012
Other income | 3,291 | 3,868 | 6,532 | 4,819
Total revenues | 614,485 | 568,747 | 1,214,954 | 1,120,221
Standard Commercial Lines [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 446,610 | 414,844 | 887,884 | 818,423
Standard Commercial Lines [Member] | Commercial Automobile [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 108,316 | 98,896 | 215,445 | 194,315
Standard Commercial Lines [Member] | Workers Compensation [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 79,460 | 75,251 | 158,786 | 151,251
Standard Commercial Lines [Member] | General Liability [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 141,503 | 129,283 | 281,487 | 257,368
Standard Commercial Lines [Member] | Commercial Property [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 78,052 | 73,591 | 154,443 | 143,769
Standard Commercial Lines [Member] | Business Owners' Policies [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 24,989 | 24,651 | 49,834 | 48,555
Standard Commercial Lines [Member] | Bonds Segment [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 6,986 | 5,665 | 13,484 | 11,129
Standard Commercial Lines [Member] | Other Commercial [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 4,288 | 3,940 | 8,529 | 7,779
Standard Commercial Lines [Member] | Miscellaneous Income [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 3,016 | 3,567 | 5,876 | 4,257
Standard Personal Lines [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 71,947 | 71,125 | 143,529 | 141,590
Standard Personal Lines [Member] | Miscellaneous Income [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 275 | 301 | 656 | 561
Standard Personal Lines [Member] | Personal Automobile [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 37,663 | 35,881 | 74,613 | 71,661
Standard Personal Lines [Member] | Homeowners [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 32,467 | 33,411 | 65,167 | 66,311
Standard Personal Lines [Member] | Other Personal [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 1,542 | 1,532 | 3,093 | 3,057
Excess And Surplus Operations [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 52,764 | 49,831 | 104,003 | 99,196
Excess And Surplus Operations [Member] | General Liability [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 39,054 | 36,940 | 76,966 | 73,796
Excess And Surplus Operations [Member] | Commercial Property [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | 13,710 | 12,891 | 27,037 | 25,399
Excess And Surplus Operations [Member] | Miscellaneous Income [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total net premiums earned | $ 0 | $ 0 | $ 0 | $ 1

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