CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues
Insurance premiums and contract charges earned	$ 759,146	$ 731,880	$ 715,760
Net investment income	361,186	332,600	329,815
Net realized investment gains	4,123	12,713	10,917
Other income	4,455	3,255	4,193
Total revenues	1,128,910	1,080,448	1,060,685
Benefits, losses and expenses
Benefits, claims and settlement expenses	541,004	496,364	468,426
Interest credited	192,022	182,842	176,139
Policy acquisition expenses amortized	96,732	98,919	93,817
Operating expenses	173,112	157,411	161,992
Interest expense	11,808	13,122	14,198
Debt retirement costs	0	2,338	0
Total benefits, losses and expenses	1,014,678	950,996	914,572
Income before income taxes	114,232	129,452	146,113
Income tax expense	30,467	35,970	41,870
Net income	$ 83,765	$ 93,482	$ 104,243
Net income per share
Basic	$ 2.04	$ 2.23	$ 2.5
Diluted	$ 2.02	$ 2.2	$ 2.47
Weighted average number of shares and equivalent shares
Basic	41,158,349	41,914,864	41,646,281
Diluted	41,475,516	42,424,806	42,230,559
Net realized investment gains
Total other-than-temporary impairment losses on securities	$ (11,401)	$ (23,796)	$ (6,385)
Portion of losses recognized in other comprehensive income (loss)	(290)	(4,300)	0
Net other-than-temporary impairment losses on securities recognized in earnings	(11,111)	(19,496)	(6,385)
Realized gains, net	15,234	32,209	17,302
Total	$ 4,123	$ 12,713	$ 10,917