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Parent Corporation Statements of Income (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2016 | Sep. 30, 2016 | Jun. 30, 2016 | Mar. 31, 2016 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Revenues: |  |  |  |  |  |  |  |  |  |  |
Dividends from subsidaries |  |  |  |  |  |  |  |  | $ (80,100) |  |
Net investment income earned | $ 42,587 | $ 40,446 | $ 41,430 | $ 37,419 | $ 35,428 | $ 33,375 | $ 31,182 | $ 30,769 | 161,882 | $ 130,754 | $ 121,316
Realized Investment Gains (Losses) |  |  |  |  |  |  |  |  | 6,359 | (4,937) | 13,171
Total revenues | 633,737 | 621,293 | 614,485 | 600,469 | 582,358 | 581,691 | 568,747 | 551,474 | 2,469,984 | 2,284,270 | 2,131,852
Expenses: |  |  |  |  |  |  |  |  |  |  |
Interest expense |  |  |  |  |  |  |  |  | 24,354 | 22,771 | 22,428
Total expenses |  |  |  |  |  |  |  |  | 2,208,016 | 2,064,315 | 1,899,160
Federal income tax (benefit) expense: |  |  |  |  |  |  |  |  |  |  |
Current |  |  |  |  |  |  |  |  | 62,184 | 48,581 | 45,347
Deferred |  |  |  |  |  |  |  |  | 30,958 | 12,879 | 21,484
Total federal income tax expense |  |  |  |  |  |  |  |  | 93,142 | 61,460 | 66,831
Net income | $ 30,242 | $ 46,718 | $ 41,426 | $ 50,440 | $ 39,360 | $ 38,502 | $ 43,601 | $ 37,032 | 168,826 | 158,495 | 165,861
Parent Company [Member] |  |  |  |  |  |  |  |  |  |  |
Revenues: |  |  |  |  |  |  |  |  |  |  |
Dividends from subsidaries |  |  |  |  |  |  |  |  | 80,096 | 61,014 | 57,752
Net investment income earned |  |  |  |  |  |  |  |  | 2,044 | 1,259 | 852
Realized Investment Gains (Losses) |  |  |  |  |  |  |  |  | (15) | (220) | 0
Total revenues |  |  |  |  |  |  |  |  | 82,125 | 62,053 | 58,604
Expenses: |  |  |  |  |  |  |  |  |  |  |
Interest expense |  |  |  |  |  |  |  |  | 24,721 | 24,030 | 24,057
Other expenses |  |  |  |  |  |  |  |  | 36,251 | 35,020 | 28,393
Total expenses |  |  |  |  |  |  |  |  | 60,972 | 59,050 | 52,450
Income before federal income tax |  |  |  |  |  |  |  |  | 21,153 | 3,003 | 6,154
Federal income tax (benefit) expense: |  |  |  |  |  |  |  |  |  |  |
Current |  |  |  |  |  |  |  |  | (22,187) | (17,924) | (16,609)
Deferred |  |  |  |  |  |  |  |  | 6,311 | (2,143) | (1,603)
Total federal income tax expense |  |  |  |  |  |  |  |  | (15,876) | (20,067) | (18,212)
Net income before equity in undistributed income of subsidiaries |  |  |  |  |  |  |  |  | 37,029 | 23,070 | 24,366
Equity In Undistributed Income Of Continuing Subsidiaries, Net Of Tax |  |  |  |  |  |  |  |  | 131,797 | 135,425 | 141,495
Net income |  |  |  |  |  |  |  |  | $ 168,826 | $ 158,495 | $ 165,861

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