Segment Information (Schedule Of Segment Reporting Information, By Segment) (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Revenues - external customers, Premiums	$ 8,852,536	$ 8,134,645	$ 26,468,203	$ 24,673,259
Total services revenue	356,212	128,917	1,034,663	394,639
Total revenues - external customers	9,208,748	8,263,562	27,502,866	25,067,898
Total intersegment revenues	0	0	0	0
Investment income	91,895	87,250	272,626	252,495
Total revenues	9,300,643	8,350,812	27,775,492	25,320,393
Operating expenses, Benefits	7,146,530	6,641,264	21,761,052	20,327,742
Operating expenses, Operating costs	1,361,657	1,002,398	3,809,905	3,156,945
Operating expenses, Depreciation and amortization	66,671	58,717	200,561	181,957
Total operating expenses	8,574,858	7,702,379	25,771,518	23,666,644
Income from operations	725,785	648,433	2,003,974	1,653,749
Interest expense	27,065	26,143	81,956	78,679
Income before income taxes	698,720	622,290	1,922,018	1,575,070
Health And Well-Being Services [Member] | Products [Member]
Total intersegment revenues	461,213	342,777	1,329,722	936,673
Retail [Member] | Products [Member]
Total intersegment revenues	0	0	0	0
Employer Group [Member] | Products [Member]
Total intersegment revenues	0	0	0	0
Other Businesses [Member] | Products [Member]
Total intersegment revenues	0	0	0	0
Products [Member]
Total intersegment revenues	0	0	0	0
Products [Member] | Eliminations/Corporate [Member]
Total intersegment revenues	(461,213)	(342,777)	(1,329,722)	(936,673)
Retail [Member]
Revenues - external customers, Premiums	5,399,654	4,791,627	16,100,794	14,364,538
Total services revenue	4,597	3,116	11,364	8,457
Total revenues - external customers	5,404,251	4,794,743	16,112,158	14,372,995
Total intersegment revenues	0	0	0	0
Investment income	19,023	21,265	56,968	62,002
Total revenues	5,423,274	4,816,008	16,169,126	14,434,997
Operating expenses, Benefits	4,249,209	3,879,424	13,193,598	11,796,751
Operating expenses, Operating costs	602,878	461,038	1,625,423	1,512,779
Operating expenses, Depreciation and amortization	29,738	27,625	88,598	86,826
Total operating expenses	4,881,825	4,368,087	14,907,619	13,396,356
Income from operations	541,449	447,921	1,261,507	1,038,641
Interest expense	0	0	0	0
Income before income taxes	541,449	447,921	1,261,507	1,038,641
Retail [Member] | Medicare Advantage [Member]
Revenues - external customers, Premiums	4,566,087	4,075,532	13,645,876	12,241,366
Retail [Member] | Medicare Stand-Alone PDP [Member]
Revenues - external customers, Premiums	578,786	504,929	1,737,603	1,512,738
Retail [Member] | Medicare [Member]
Revenues - external customers, Premiums	5,144,873	4,580,461	15,383,479	13,754,104
Retail [Member] | Fully-Insured [Member]
Revenues - external customers, Premiums	221,632	189,503	628,811	551,581
Retail [Member] | Specialty [Member]
Revenues - external customers, Premiums	33,149	21,663	88,504	58,853
Retail [Member] | Military Services [Member]
Revenues - external customers, Premiums	0	0	0	0
Retail [Member] | Medicaid And Other [Member]
Revenues - external customers, Premiums	0	0	0	0
Retail [Member] | Provider [Member]
Total services revenue	0	0	0	0
Retail [Member] | ASO And Other [Member]
Total services revenue	4,597	3,116	11,364	8,457
Retail [Member] | Pharmacy [Member]
Total services revenue	0	0	0	0
Retail [Member] | Services [Member]
Total intersegment revenues	0	0	0	0
Employer Group [Member]
Revenues - external customers, Premiums	2,225,202	2,217,290	6,668,354	6,830,936
Total services revenue	88,699	94,884	267,902	294,241
Total revenues - external customers	2,313,901	2,312,174	6,936,256	7,125,177
Total intersegment revenues	3,715	3,224	10,313	9,892
Investment income	11,879	11,165	35,287	32,412
Total revenues	2,329,495	2,326,563	6,981,856	7,167,481
Operating expenses, Benefits	1,856,934	1,818,752	5,408,049	5,586,593
Operating expenses, Operating costs	405,853	407,117	1,216,685	1,250,446
Operating expenses, Depreciation and amortization	20,851	21,704	64,101	70,219
Total operating expenses	2,283,638	2,247,573	6,688,835	6,907,258
Income from operations	45,857	78,990	293,021	260,223
Interest expense	0	0	0	0
Income before income taxes	45,857	78,990	293,021	260,223
Employer Group [Member] | Medicare Advantage [Member]
Revenues - external customers, Premiums	802,957	723,378	2,364,306	2,259,733
Employer Group [Member] | Medicare Stand-Alone PDP [Member]
Revenues - external customers, Premiums	1,910	1,153	5,638	3,443
Employer Group [Member] | Medicare [Member]
Revenues - external customers, Premiums	804,867	724,531	2,369,944	2,263,176
Employer Group [Member] | Fully-Insured [Member]
Revenues - external customers, Premiums	1,185,285	1,275,945	3,600,476	3,904,705
Employer Group [Member] | Specialty [Member]
Revenues - external customers, Premiums	235,050	216,814	697,934	663,055
Employer Group [Member] | Military Services [Member]
Revenues - external customers, Premiums	0	0	0	0
Employer Group [Member] | Medicaid And Other [Member]
Revenues - external customers, Premiums	0	0	0	0
Employer Group [Member] | Provider [Member]
Total services revenue	0	0	0	0
Employer Group [Member] | ASO And Other [Member]
Total services revenue	88,699	94,884	267,902	294,241
Employer Group [Member] | Pharmacy [Member]
Total services revenue	0	0	0	0
Employer Group [Member] | Services [Member]
Total intersegment revenues	3,715	3,224	10,313	9,892
Health And Well-Being Services [Member]
Revenues - external customers, Premiums	0	0	0	0
Total services revenue	236,472	3,815	678,738	9,869
Total revenues - external customers	236,472	3,815	678,738	9,869
Total intersegment revenues	2,591,128	2,186,012	7,654,714	6,611,638
Investment income	0	0	0	0
Total revenues	2,827,600	2,189,827	8,333,452	6,621,507
Operating expenses, Benefits	0	0	0	0
Operating expenses, Operating costs	2,723,334	2,106,079	8,004,784	6,427,167
Operating expenses, Depreciation and amortization	20,701	8,211	60,927	19,703
Total operating expenses	2,744,035	2,114,290	8,065,711	6,446,870
Income from operations	83,565	75,537	267,741	174,637
Interest expense	0	0	0	0
Income before income taxes	83,565	75,537	267,741	174,637
Health And Well-Being Services [Member] | Medicare Advantage [Member]
Revenues - external customers, Premiums	0	0	0	0
Health And Well-Being Services [Member] | Medicare Stand-Alone PDP [Member]
Revenues - external customers, Premiums	0	0	0	0
Health And Well-Being Services [Member] | Medicare [Member]
Revenues - external customers, Premiums	0	0	0	0
Health And Well-Being Services [Member] | Fully-Insured [Member]
Revenues - external customers, Premiums	0	0	0	0
Health And Well-Being Services [Member] | Specialty [Member]
Revenues - external customers, Premiums	0	0	0	0
Health And Well-Being Services [Member] | Military Services [Member]
Revenues - external customers, Premiums	0	0	0	0
Health And Well-Being Services [Member] | Medicaid And Other [Member]
Revenues - external customers, Premiums	0	0	0	0
Health And Well-Being Services [Member] | Provider [Member]
Total services revenue	233,608	3,815	671,055	9,869
Health And Well-Being Services [Member] | ASO And Other [Member]
Total services revenue	0	0	0	0
Health And Well-Being Services [Member] | Pharmacy [Member]
Total services revenue	2,864	0	7,683	0
Health And Well-Being Services [Member] | Services [Member]
Total intersegment revenues	2,129,915	1,843,235	6,324,992	5,674,965
Other Businesses [Member]
Revenues - external customers, Premiums	1,227,680	1,125,728	3,699,055	3,477,785
Total services revenue	26,444	27,102	76,659	82,072
Total revenues - external customers	1,254,124	1,152,830	3,775,714	3,559,857
Total intersegment revenues	0	0	0	0
Investment income	14,324	11,482	39,999	31,363
Total revenues	1,268,448	1,164,312	3,815,713	3,591,220
Operating expenses, Benefits	1,116,702	1,021,082	3,375,461	3,125,564
Operating expenses, Operating costs	121,574	118,551	351,145	348,611
Operating expenses, Depreciation and amortization	2,450	2,664	6,802	8,684
Total operating expenses	1,240,726	1,142,297	3,733,408	3,482,859
Income from operations	27,722	22,015	82,305	108,361
Interest expense	0	0	0	0
Income before income taxes	27,722	22,015	82,305	108,361
Other Businesses [Member] | Medicare Advantage [Member]
Revenues - external customers, Premiums	0	0	0	0
Other Businesses [Member] | Medicare Stand-Alone PDP [Member]
Revenues - external customers, Premiums	42,524	73,501	195,604	342,649
Other Businesses [Member] | Medicare [Member]
Revenues - external customers, Premiums	42,524	73,501	195,604	342,649
Other Businesses [Member] | Fully-Insured [Member]
Revenues - external customers, Premiums	0	0	0	0
Other Businesses [Member] | Specialty [Member]
Revenues - external customers, Premiums	0	0	0	0
Other Businesses [Member] | Military Services [Member]
Revenues - external customers, Premiums	943,984	873,588	2,801,999	2,603,950
Other Businesses [Member] | Medicaid And Other [Member]
Revenues - external customers, Premiums	241,172	178,639	701,452	531,186
Other Businesses [Member] | Provider [Member]
Total services revenue	0	0	0	0
Other Businesses [Member] | ASO And Other [Member]
Total services revenue	26,444	27,102	76,659	82,072
Other Businesses [Member] | Pharmacy [Member]
Total services revenue	0	0	0	0
Other Businesses [Member] | Services [Member]
Total intersegment revenues	0	0	0	0
Eliminations/Corporate [Member]
Revenues - external customers, Premiums	0	0	0	0
Total services revenue	0	0	0	0
Total revenues - external customers	0	0	0	0
Total intersegment revenues	(2,594,843)	(2,189,236)	(7,665,027)	(6,621,530)
Investment income	46,669	43,338	140,372	126,718
Total revenues	(2,548,174)	(2,145,898)	(7,524,655)	(6,494,812)
Operating expenses, Benefits	(76,315)	(77,994)	(216,056)	(181,166)
Operating expenses, Operating costs	(2,491,982)	(2,090,387)	(7,388,132)	(6,382,058)
Operating expenses, Depreciation and amortization	(7,069)	(1,487)	(19,867)	(3,475)
Total operating expenses	(2,575,366)	(2,169,868)	(7,624,055)	(6,566,699)
Income from operations	27,192	23,970	99,400	71,887
Interest expense	27,065	26,143	81,956	78,679
Income before income taxes	127	(2,173)	17,444	(6,792)
Eliminations/Corporate [Member] | Medicare Advantage [Member]
Revenues - external customers, Premiums	0	0	0	0
Eliminations/Corporate [Member] | Medicare Stand-Alone PDP [Member]
Revenues - external customers, Premiums	0	0	0	0
Eliminations/Corporate [Member] | Medicare [Member]
Revenues - external customers, Premiums	0	0	0	0
Eliminations/Corporate [Member] | Fully-Insured [Member]
Revenues - external customers, Premiums	0	0	0	0
Eliminations/Corporate [Member] | Specialty [Member]
Revenues - external customers, Premiums	0	0	0	0
Eliminations/Corporate [Member] | Military Services [Member]
Revenues - external customers, Premiums	0	0	0	0
Eliminations/Corporate [Member] | Medicaid And Other [Member]
Revenues - external customers, Premiums	0	0	0	0
Eliminations/Corporate [Member] | Provider [Member]
Total services revenue	0	0	0	0
Eliminations/Corporate [Member] | ASO And Other [Member]
Total services revenue	0	0	0	0
Eliminations/Corporate [Member] | Pharmacy [Member]
Total services revenue	0	0	0	0
Eliminations/Corporate [Member] | Services [Member]
Total intersegment revenues	(2,133,630)	(1,846,459)	(6,335,305)	(5,684,857)
Medicare Advantage [Member]
Revenues - external customers, Premiums	5,369,044	4,798,910	16,010,182	14,501,099
Medicare Stand-Alone PDP [Member]
Revenues - external customers, Premiums	623,220	579,583	1,938,845	1,858,830
Medicare [Member]
Revenues - external customers, Premiums	5,992,264	5,378,493	17,949,027	16,359,929
Fully-Insured [Member]
Revenues - external customers, Premiums	1,406,917	1,465,448	4,229,287	4,456,286
Specialty [Member]
Revenues - external customers, Premiums	268,199	238,477	786,438	721,908
Military Services [Member]
Revenues - external customers, Premiums	943,984	873,588	2,801,999	2,603,950
Medicaid And Other [Member]
Revenues - external customers, Premiums	241,172	178,639	701,452	531,186
Provider [Member]
Total services revenue	233,608	3,815	671,055	9,869
ASO And Other [Member]
Total services revenue	119,740	125,102	355,925	384,770
Pharmacy [Member]
Total services revenue	2,864	0	7,683	0
Services [Member]
Total intersegment revenues	$ 0	$ 0	$ 0	$ 0