Income Taxes (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
|
| Income Tax Disclosure [Abstract] | ||||
| Federal statutory income tax rate (percent) | 35.00% | |||
| Income tax reconciliation | ||||
| Earnings before income taxes | $ 3,196 | $ 22,814 | $ 30,012 | $ 58,717 |
| Income taxes at statutory rate | 1,119 | 7,985 | 10,504 | 20,551 |
| Dividends-received deduction | (101) | (89) | (322) | (337) |
| Tax-exempt interest | (600) | (725) | (1,858) | (2,033) |
| Other | 24 | (94) | 212 | 152 |
| Provision for income taxes as shown on the Consolidated Statements of Earnings | $ 442 | $ 7,077 | $ 8,536 | $ 18,333 |
| GAAP effective tax rate (percent) | 13.80% | 31.00% | 28.40% | 31.20% |