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Schedule II. Condensed Financial Information of Registrant - Condensed Statements of Income (Detail) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Revenues |  |  |  |  |  |  |  |  |  |  |
Net investment income | $ 8,056 | $ 7,884 | $ 7,303 | $ 7,209 | $ 7,312 | $ 7,788 | $ 7,471 | $ 6,710 | $ 30,452 | $ 29,281 | $ 28,106
Net unrealized losses on equity securities |  |  |  |  |  |  |  |  | (2,088) |  |
Fee and other income |  |  |  |  |  |  |  |  | 599 | 418 | 346
Total revenues | 94,669 | 93,529 | 95,380 | 94,175 | 94,937 | 92,804 | 89,925 | 97,542 | 377,753 | 375,208 | 396,662
Expenses |  |  |  |  |  |  |  |  |  |  |
Total expenses |  |  |  |  |  |  |  |  | 290,172 | 292,968 | 283,841
Income tax expense (benefit) |  |  |  |  |  |  |  |  | 15,949 | 36,009 | 34,956
Net income | $ 18,806 | $ 19,701 | $ 16,956 | $ 16,169 | $ 649 | $ 16,577 | $ 15,481 | $ 13,524 | 71,632 | 46,231 | 77,865
Parent Company [Member] |  |  |  |  |  |  |  |  |  |  |
Revenues |  |  |  |  |  |  |  |  |  |  |
Net investment income |  |  |  |  |  |  |  |  | 1,089 | 679 | 1,509
Net unrealized losses on equity securities |  |  |  |  |  |  |  |  | (948) |  |
Fee and other income |  |  |  |  |  |  |  |  | 7,389 | 6,890 | 5,843
Total revenues |  |  |  |  |  |  |  |  | 7,530 | 7,569 | 7,352
Expenses |  |  |  |  |  |  |  |  |  |  |
Other operating costs |  |  |  |  |  |  |  |  | 7,530 | 7,569 | 7,352
Total expenses |  |  |  |  |  |  |  |  | 7,530 | 7,569 | 7,352
Income tax expense (benefit) |  |  |  |  |  |  |  |  | (36) | 125 | (156)
Gain (loss) before equity in earnings of subsidiaries |  |  |  |  |  |  |  |  | 36 | (125) | 156
Equity in net income of subsidiaries |  |  |  |  |  |  |  |  | 71,596 | 46,356 | 77,709
Net income |  |  |  |  |  |  |  |  | $ 71,632 | $ 46,231 | $ 77,865

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