Business Segments (Reconciliation Of Revenues And Operations By Segment To Its Major Income Statement Line Items) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended														9 Months Ended		12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009		Dec. 31, 2011 Life Insurance [Member]	Dec. 31, 2010 Life Insurance [Member]		Dec. 31, 2009 Life Insurance [Member]	Dec. 31, 2011 Health Insurance [Member]	Dec. 31, 2010 Health Insurance [Member]		Dec. 31, 2009 Health Insurance [Member]	Sep. 30, 2010 Annuity [Member]		Dec. 31, 2011 Annuity [Member]	Dec. 31, 2010 Annuity [Member]	Dec. 31, 2009 Annuity [Member]	Dec. 31, 2011 Investment [Member]	Dec. 31, 2010 Investment [Member]		Dec. 31, 2009 Investment [Member]	Dec. 31, 2011 Other Segments [Member]		Dec. 31, 2010 Other Segments [Member]		Dec. 31, 2009 Other Segments [Member]		Dec. 31, 2011 Corporate [Member]	Dec. 31, 2010 Corporate [Member]	Dec. 31, 2009 Corporate [Member]	Dec. 31, 2011 Adjustments [Member]		Dec. 31, 2010 Adjustments [Member]		Dec. 31, 2009 Adjustments [Member]
Segment Reporting Information [Line Items]
Premium	$ 653,542	$ 650,525	$ 672,350	$ 679,901	$ 653,418	$ 657,827	$ 669,569	$ 670,944	$ 2,656,318		$ 2,651,758		$ 2,610,105		$ 1,726,244	$ 1,663,699		$ 1,591,853	$ 930,493	$ 987,937		$ 1,020,202			$ 608	$ 638	$ 541														$ (1,027)	[1]	$ (516)	[1]	$ (2,491)	[1]
Net investment income	174,786	173,491	173,104	171,647	166,304	172,337	170,612	167,111	693,028		676,364		632,540															707,041	685,253		632,276										(14,013)	[2],[3]	(8,889)	[2],[4]	264	[2]
Other income									2,151		2,170		1,920																			2,507		2,834		2,914					(356)	[5]	(664)	[5]	(994)	[5]
Total revenue									3,351,497		3,330,292		3,244,565		1,726,244	1,663,699		1,591,853	930,493	987,937		1,020,202			608	638	541	707,041	685,253		632,276	2,507		2,834		2,914					(15,396)		(10,069)		(3,221)
Policy benefits	435,681	438,774	454,694	464,127	436,419	433,514	454,177	468,934	1,793,276		1,793,044		1,753,329		1,118,909	1,082,423		1,040,248	632,847	669,707		679,810			42,547	41,430	35,762														(1,027)	[1]	(516)	[1]	(2,491)	[1]
Required interest on net reserves									0		0		0		(458,029)	(434,319)		(410,917)	(36,729)	(35,368)		(34,243)			(57,040)	(51,996)	(41,840)	551,798	521,683		487,000
Amortization of acquisition costs	105,437	104,804	106,752	107,788	100,392	104,045	104,851	109,602	424,781		418,890		415,986		503,649	487,770		462,837	123,442	130,238		147,151			12,688	9,722	6,040	(214,998)	(208,840)		(200,042)
Commissions and premium tax									124,134		125,330		128,620		75,480	72,559		72,273	48,942	53,301		57,074			68	134	267														(356)	[5]	(664)	[5]	(994)	[5]
Insurance administrative expense									178,989	[6]	155,615	[6]	150,680	[6]																		159,109	[6]	155,615	[6]	150,325	[6]				19,880	[6],[7],[8],[9]			355	[10],[6]
Parent expense									7,693		8,809		9,590																									7,693	8,809	9,590
Stock-based compensation expense									14,954		11,848		9,860																									14,954	11,848	9,860
Interest expense									77,908		75,529		69,932															77,644	75,265		69,668										264	[2]	264	[2]	264	[2]
Total benefits and expenses									2,621,735		2,589,065		2,537,997		1,240,009	1,208,433		1,164,441	768,502	817,878		849,792			(1,737)	(710)	229	414,444	388,108		356,626	159,109		155,615		150,325		22,647	20,657	19,450	18,761		(916)		(2,866)
Subtotal									729,762		741,227		706,568		486,235	455,266		427,412	161,991	170,059		170,410			2,345	1,348	312	292,597	297,145		275,650	(156,602)		(152,781)		(147,411)		(22,647)	(20,657)	(19,450)	(34,157)		(9,153)		(355)
Nonoperating items									19,880				355																												19,880	[7],[8],[9]			355	[10]
Measure of segment profitability (pretax)									763,919		750,380	[11]	706,923		486,235	455,266	[11]	427,412	161,991	170,059	[11]	170,410	1,348	[11]	2,345	1,348	312	292,597	297,145	[11]	275,650	(156,602)		(152,781)		(147,411)		(22,647)	(20,657)	(19,450)	0		0		0
Deduct applicable income taxes									(249,495)		(252,357)	[11]	(238,153)
After-tax total net operating income, before discontinued operations									514,424		498,023	[11]	468,770
Add back income taxes applicable to segment profitability									249,495		252,357		238,153
Add (deduct) realized investment gains (losses)									25,904		37,340		(129,492)
Deduct loss on Company-occupied property													(355)	[10]
Deduct amortization of low-income housing									(14,277)	[3]	(9,153)	[4]
Deduct state administrative settlement expense									(6,901)	[7]
Deduct loss on sale of equipment									(979)	[8]
Deduct litigation expense									(12,000)	[9]
Income from continuing operations before income taxes	$ 182,504	$ 198,822	$ 218,528	$ 155,812	$ 215,480	$ 208,313	$ 180,720	$ 174,054	$ 755,666		$ 778,567		$ 577,076

[1] Medicare Part D items adjusted to GAAP from the segment analysis, which matches expected benefits with policy premium.

[2] Reclassification of interest amount due to accounting rule requiring deconsolidation of Trust Preferred Securities.

[3] Amortization of low-income housing interests.

[4] Amortization of low-income housing interests, previously considered a reduction of consolidated pretax segment profitability.

[5] Elimination of intersegment commission.

[6] Administrative expense is not allocated to insurance segments.

[7] State administrative settlement expense.

[8] Loss on sale of equipment.

[9] Litigation expense.

[10] Loss on Company-occupied property.

[11] During 2011, management changed the definition of total segment profits before tax to exclude the amortization of low-income housing interests, which management views as a tax expense. Accordingly, the 2010 total segment profits before tax and applicable tax amount have been updated for comparison purposes.