Consolidated Statements of Changes in Stockholder's Equity - USD ($) $ in Thousands	Total		Series B Preferred Stock	Class A and Class B Common Stock	Accumulated Other Comprehensive Income	Retained Earnings	Non- controlling Interest
Balance at Dec. 31, 2017	$ 1,377,125		$ 3,000	$ 153,661	$ 284,983	$ 935,423	$ 58
Cumulative Effect on Retained Earnings, Net of Tax | Accounting Standards Update 2016-01	0				(5,480)	5,480
Net income	56,327					56,368	(41)
Other comprehensive loss	(148,422)	[1]			(148,422)
Stock-based compensation	320			320
Purchase of common stock	(8,849)			(795)		(8,054)
Dividends on preferred stock	(75)					(75)
Dividends on common stock	(60,169)					(60,169)
Noncontrolling Interest, Period Increase (Decrease)	15						15
Balance at Jun. 30, 2018	1,216,272		3,000	153,186	131,081	928,973	32
Balance at Mar. 31, 2018	1,252,396		3,000	153,267	186,222	909,872	35
Cumulative Effect on Retained Earnings, Net of Tax | Accounting Standards Update 2016-01	0				389	(389)
Net income	32,785					32,803	(18)
Other comprehensive loss	(55,530)	[1]			(55,530)
Stock-based compensation	102			102
Purchase of common stock	(2,043)			(183)		(1,860)
Dividends on preferred stock	(37)					(37)
Dividends on common stock	(11,416)					(11,416)
Noncontrolling Interest, Period Increase (Decrease)	15						15
Balance at Jun. 30, 2018	1,216,272		3,000	153,186	131,081	928,973	32
Balance at Dec. 31, 2018	1,184,259		3,000	152,724	91,318	937,097	120
Cumulative Effect on Retained Earnings, Net of Tax | Accounting Standards Update 2016-02 [Member]	595				0	595
Net income	66,301					66,341	(40)
Other comprehensive loss	211,475	[1]			211,475
Stock-based compensation	212			212
Purchase of common stock	(4,577)			(410)		(4,167)
Dividends on preferred stock	(75)					(75)
Dividends on common stock	(60,648)					(60,648)
Balance at Jun. 30, 2019	1,397,542		3,000	152,526	302,793	939,143	80
Balance at Mar. 31, 2019	1,263,521		3,000	152,516	189,166	918,718	121
Net income	32,257					32,298	(41)
Other comprehensive loss	113,627	[1]			113,627
Stock-based compensation	10			10
Dividends on preferred stock	(37)					(37)
Dividends on common stock	(11,836)					(11,836)
Balance at Jun. 30, 2019	$ 1,397,542		$ 3,000	$ 152,526	$ 302,793	$ 939,143	$ 80

[1] Other comprehensive income (loss) is recorded net of deferred income taxes and other adjustments for assumed changes in deferred acquisition costs, value of insurance in force acquired, unearned revenue reserve and policyholder liabilities.