CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues
Insurance premiums and contract charges earned	$ 690,938	$ 670,527	$ 667,120
Net investment income	313,610	306,003	288,311
Net realized investment gains	22,245	27,298	37,663
Other income	4,474	6,986	5,208
Total revenues	1,031,267	1,010,814	998,302
Benefits, losses and expenses
Benefits, claims and settlement expenses	448,317	448,250	502,434
Interest credited	169,893	163,565	154,910
Policy acquisition expenses amortized	84,643	79,519	83,398
Operating expenses	160,112	156,058	148,635
Interest expense	14,236	14,249	14,007
Total benefits, losses and expenses	877,201	861,641	903,384
Income before income taxes	154,066	149,173	94,918
Income tax expense	43,173	45,307	24,412
Net income	110,893	103,866	70,506
Net income per share
Basic	$ 2.75	$ 2.63	$ 1.77
Diluted	$ 2.66	$ 2.51	$ 1.70
Weighted average number of shares and equivalent shares
Basic	40,376,562	39,513,540	39,865,815
Diluted	41,633,240	41,388,368	41,436,512
Net realized investment gains
Total other-than-temporary impairment losses on securities	(1,532)	0	(72)
Portion of losses recognized in other comprehensive income (loss)	0	0	0
Net other-than-temporary impairment losses on securities recognized in earnings	(1,532)	0	(72)
Realized gains, net	23,777	27,298	37,735
Total	$ 22,245	$ 27,298	$ 37,663