Consolidated Statements Of Operations (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenues
Insurance premiums and contract charges earned	$ 667,118	$ 672,675	$ 659,590
Net investment income	288,311	272,054	246,834
Net realized investment gains	37,663	23,769	26,310
Other income	5,208	6,213	4,693
Total revenues	998,300	974,711	937,427
Benefits, losses and expenses
Benefits, claims and settlement expenses	502,441	474,836	458,660
Interest credited	154,910	146,723	139,421
Policy acquisition expenses amortized	92,128	85,056	80,399
Operating expenses	139,936	142,852	141,246
Amortization of intangible assets			223
Interest expense	14,007	13,953	13,971
Total benefits, losses and expenses	903,422	863,420	833,920
Income before income taxes	94,878	111,291	103,507
Income tax expense	24,398	30,429	30,021
Net income	70,480	80,862	73,486
Earnings per share
Basic	$ 1.77	$ 2.05	$ 1.88
Diluted	$ 1.70	$ 1.97	$ 1.81
Weighted average number of shares and equivalent shares
Basic	39,865,815	39,349,656	39,175,258
Diluted	41,436,512	41,013,163	40,532,174
Net realized investment gains
Total other-than-temporary impairment losses on securities	(72)	(7,255)	(22,724)
Portion of losses recognized in other comprehensive income		459	1,430
Net other-than-temporary impairment loss write-downs on securities recognized in earnings	(72)	(6,796)	(21,294)
Realized gains	37,735	30,565	47,604
Total	$ 37,663	$ 23,769	$ 26,310