CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues
Insurance premiums and contract charges earned	$ 731,880	$ 715,760	$ 690,938
Net investment income	332,600	329,815	313,610
Net realized investment gains	12,713	10,917	22,245
Other income	3,255	4,193	4,474
Total revenues	1,080,448	1,060,685	1,031,267
Benefits, losses and expenses
Benefits, claims and settlement expenses	496,364	468,426	448,317
Interest credited	182,842	176,139	169,893
Policy acquisition expenses amortized	98,919	93,817	84,643
Operating expenses	157,411	161,992	160,112
Interest expense	13,122	14,198	14,236
Debt retirement costs	2,338	0	0
Total benefits, losses and expenses	950,996	914,572	877,201
Income before income taxes	129,452	146,113	154,066
Income tax expense	35,970	41,870	43,173
Net income	$ 93,482	$ 104,243	$ 110,893
Net income per share
Basic	$ 2.23	$ 2.5	$ 2.75
Diluted	$ 2.20	$ 2.47	$ 2.66
Weighted average number of shares and equivalent shares
Basic	41,914,864	41,646,281	40,376,562
Diluted	42,424,806	42,230,559	41,633,240
Net realized investment gains
Total other-than-temporary impairment losses on securities	$ (23,796)	$ (6,385)	$ (1,532)
Portion of losses recognized in other comprehensive income (loss)	(4,300)	0	0
Net other-than-temporary impairment losses on securities recognized in earnings	(19,496)	(6,385)	(1,532)
Realized gains, net	32,209	17,302	23,777
Total	$ 12,713	$ 10,917	$ 22,245