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v3.20.1

Segment Information (Revenue by Segment) (Details) - USD ($) $ in Thousands | 3 Months Ended
--- | ---
Mar. 31, 2020 | Mar. 31, 2019
Segment Reporting Information [Line Items] |  |
Total net premiums earned | $ 651,703 | $ 632,573
Miscellaneous income | 1,825 | 2,320
Net investment income | 55,967 | 50,618
Net realized and unrealized investment (losses) gains | (44,666) | 13,451
Total Investments revenue | 11,301 | 64,069
Total revenues | 664,829 | 698,962
Standard Commercial Lines [Member] |  |
Segment Reporting Information [Line Items] |  |
Miscellaneous income | 1,391 | 2,044
Total revenues | 517,971 | 499,228
Standard Commercial Lines [Member] | Commercial Automobile [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 149,690 | 131,186
Standard Commercial Lines [Member] | Workers Compensation [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 66,706 | 78,715
Standard Commercial Lines [Member] | General Liability [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 164,580 | 161,525
Standard Commercial Lines [Member] | Commercial Property [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 93,869 | 86,067
Standard Commercial Lines [Member] | Business Owners' Policies [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 27,036 | 26,081
Standard Commercial Lines [Member] | Bonds Segment [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 9,639 | 8,904
Standard Commercial Lines [Member] | Other Commercial [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 5,060 | 4,706
Standard Personal Lines [Member] |  |
Segment Reporting Information [Line Items] |  |
Miscellaneous income | 434 | 276
Total revenues | 76,562 | 77,583
Standard Personal Lines [Member] | Personal Automobile [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 42,487 | 43,163
Standard Personal Lines [Member] | Homeowners [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 31,490 | 32,130
Standard Personal Lines [Member] | Other Personal [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 2,151 | 2,014
Excess And Surplus Operations [Member] |  |
Segment Reporting Information [Line Items] |  |
Miscellaneous income | 0 | 0
Total revenues | 58,995 | 58,082
Excess And Surplus Operations [Member] | Casualty Insurance Product Line [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | 44,072 | 44,528
Excess And Surplus Operations [Member] | Property Insurance [Member] |  |
Segment Reporting Information [Line Items] |  |
Total net premiums earned | $ 14,923 | $ 13,554

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