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Segment Information (Reconciliation of Segment Results to Income from Continuing Operations, before Federal Income Tax (Details)) (USD $) In Thousands, unless otherwise specified | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items] |  |  |  |
Investment income, before federal income tax | $ 49,523 | $ 45,888 | $ 133,588 | $ 121,270
Total all segments | 83,960 | 56,039 | 173,094 | 148,065
Interest expense | (5,558) | (5,570) | (16,544) | (16,971)
General corporate and other expenses | (3,076) | (5,984) | (16,619) | (21,540)
Income from continuing operations, before federal income tax | 75,326 | 44,485 | 139,931 | 109,554
Total Standard Insurance Operations [Member] |  |  |  |
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items] |  |  |  |
Underwriting gain (loss), before federal income tax | 35,808 | 10,138 | 39,939 | 28,981
Excess And Surplus Operations [Member] |  |  |  |
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items] |  |  |  |
Underwriting gain (loss), before federal income tax | $ (1,371) | $ 13 | $ (433) | $ (2,186)

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