Segment Information by Segment (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Premiums										$ 38,829	$ 37,009	$ 35,106
Services										2,109	1,726	1,360
Total revenues-external customers										40,938	38,735	36,466
Investment income										375	391	366
Total revenues	10,187	[1]	10,319	10,321	10,486	9,557	9,651	9,699	10,219	41,313	39,126	36,832
Benefits										32,564	30,985	28,823
Operating costs										6,355	5,830	5,395
Depreciation and amortization										333	295	270
Total operating expenses										39,252	37,110	34,488
Income from operations										2,061	2,016	2,344
Interest expense										140	105	109
Income before income taxes	(49)	[1]	586	654	730	282	675	564	390	1,921	1,911	2,235
Medicare Advantage
Segment Reporting Information [Line Items]
Premiums										27,191	24,852	21,252
Medicare Stand Alone Prescription Drug Plan
Segment Reporting Information [Line Items]
Premiums										3,033	2,861	2,578
Medicare
Segment Reporting Information [Line Items]
Premiums										30,224	27,713	23,830
Fully-Insured
Segment Reporting Information [Line Items]
Premiums										6,277	6,000	5,643
Specialty
Segment Reporting Information [Line Items]
Premiums										1,305	1,241	1,059
Military Services
Segment Reporting Information [Line Items]
Premiums										25	1,017	3,616
Medicaid And Other
Segment Reporting Information [Line Items]
Premiums										998	1,038	958
Provider
Segment Reporting Information [Line Items]
Services										1,242	1,020	892
Aso And Other
Segment Reporting Information [Line Items]
Services										808	690	457
Pharmacy
Segment Reporting Information [Line Items]
Services										59	16	11
Intersegment revenues
Segment Reporting Information [Line Items]
Total revenues										(14,702)	(12,095)	(10,527)
Intersegment revenues | Retail
Segment Reporting Information [Line Items]
Total revenues										0	2	0
Intersegment revenues | Employer Group
Segment Reporting Information [Line Items]
Total revenues										51	31	18
Intersegment revenues | Healthcare Services
Segment Reporting Information [Line Items]
Total revenues										14,651	12,062	10,509
Intersegment revenues | Other Businesses
Segment Reporting Information [Line Items]
Total revenues										0	0	0
Intersegment revenues | Services
Segment Reporting Information [Line Items]
Total revenues										(11,899)	(9,753)	(8,707)
Intersegment revenues | Services | Retail
Segment Reporting Information [Line Items]
Total revenues										0	2	0
Intersegment revenues | Services | Employer Group
Segment Reporting Information [Line Items]
Total revenues										51	31	18
Intersegment revenues | Services | Healthcare Services
Segment Reporting Information [Line Items]
Total revenues										11,848	9,720	8,689
Intersegment revenues | Services | Other Businesses
Segment Reporting Information [Line Items]
Total revenues										0	0	0
Intersegment revenues | Products
Segment Reporting Information [Line Items]
Total revenues										(2,803)	(2,342)	(1,820)
Intersegment revenues | Products | Retail
Segment Reporting Information [Line Items]
Total revenues										0	0	0
Intersegment revenues | Products | Employer Group
Segment Reporting Information [Line Items]
Total revenues										0	0	0
Intersegment revenues | Products | Healthcare Services
Segment Reporting Information [Line Items]
Total revenues										2,803	2,342	1,820
Intersegment revenues | Products | Other Businesses
Segment Reporting Information [Line Items]
Total revenues										0	0	0
Operating Segments | Retail
Segment Reporting Information [Line Items]
Premiums										27,204	25,001	21,831
Services										16	24	16
Total revenues-external customers										27,220	25,025	21,847
Investment income										74	79	76
Total revenues										27,294	25,106	21,923
Benefits										22,914	21,048	17,753
Operating costs										2,963	2,767	2,421
Depreciation and amortization										134	130	119
Total operating expenses										26,011	23,945	20,293
Income from operations										1,283	1,161	1,630
Interest expense										0	0	0
Income before income taxes										1,283	1,161	1,630
Operating Segments | Employer Group
Segment Reporting Information [Line Items]
Premiums										10,930	10,138	8,877
Services										357	370	356
Total revenues-external customers										11,287	10,508	9,233
Investment income										42	42	48
Total revenues										11,380	10,581	9,299
Benefits										9,124	8,471	7,318
Operating costs										1,832	1,744	1,675
Depreciation and amortization										102	89	88
Total operating expenses										11,058	10,304	9,081
Income from operations										322	277	218
Interest expense										0	0	0
Income before income taxes										322	277	218
Operating Segments | Healthcare Services
Segment Reporting Information [Line Items]
Premiums										0	0	0
Services										1,282	1,024	903
Total revenues-external customers										1,282	1,024	903
Investment income										0	0	0
Total revenues										15,933	13,086	11,412
Benefits										0	0	0
Operating costs										15,237	12,536	10,956
Depreciation and amortization										147	87	79
Total operating expenses										15,384	12,623	11,035
Income from operations										549	463	377
Interest expense										0	0	0
Income before income taxes										549	463	377
Operating Segments | Other Businesses
Segment Reporting Information [Line Items]
Premiums										695	1,870	4,398
Services										454	308	85
Total revenues-external customers										1,149	2,178	4,483
Investment income										59	58	54
Total revenues										1,208	2,236	4,537
Benefits										935	1,802	4,041
Operating costs										446	436	445
Depreciation and amortization										20	16	10
Total operating expenses										1,401	2,254	4,496
Income from operations										(193)	(18)	41
Interest expense										0	0	0
Income before income taxes										(193)	(18)	41
Operating Segments | Medicare Advantage | Retail
Segment Reporting Information [Line Items]
Premiums										22,481	20,788	18,100
Operating Segments | Medicare Advantage | Employer Group
Segment Reporting Information [Line Items]
Premiums										4,710	4,064	3,152
Operating Segments | Medicare Advantage | Healthcare Services
Segment Reporting Information [Line Items]
Premiums										0	0	0
Operating Segments | Medicare Advantage | Other Businesses
Segment Reporting Information [Line Items]
Premiums										0	0	0
Operating Segments | Medicare Stand Alone Prescription Drug Plan | Retail
Segment Reporting Information [Line Items]
Premiums										3,025	2,853	2,570
Operating Segments | Medicare Stand Alone Prescription Drug Plan | Employer Group
Segment Reporting Information [Line Items]
Premiums										8	8	8
Operating Segments | Medicare Stand Alone Prescription Drug Plan | Healthcare Services
Segment Reporting Information [Line Items]
Premiums										0	0	0
Operating Segments | Medicare Stand Alone Prescription Drug Plan | Other Businesses
Segment Reporting Information [Line Items]
Premiums										0	0	0
Operating Segments | Medicare | Retail
Segment Reporting Information [Line Items]
Premiums										25,506	23,641	20,670
Operating Segments | Medicare | Employer Group
Segment Reporting Information [Line Items]
Premiums										4,718	4,072	3,160
Operating Segments | Medicare | Healthcare Services
Segment Reporting Information [Line Items]
Premiums										0	0	0
Operating Segments | Medicare | Other Businesses
Segment Reporting Information [Line Items]
Premiums										0	0	0
Operating Segments | Fully-Insured | Retail
Segment Reporting Information [Line Items]
Premiums										1,160	1,004	861
Operating Segments | Fully-Insured | Employer Group
Segment Reporting Information [Line Items]
Premiums										5,117	4,996	4,782
Operating Segments | Fully-Insured | Healthcare Services
Segment Reporting Information [Line Items]
Premiums										0	0	0
Operating Segments | Fully-Insured | Other Businesses
Segment Reporting Information [Line Items]
Premiums										0	0	0
Operating Segments | Specialty | Retail
Segment Reporting Information [Line Items]
Premiums										210	171	124
Operating Segments | Specialty | Employer Group
Segment Reporting Information [Line Items]
Premiums										1,095	1,070	935
Operating Segments | Specialty | Healthcare Services
Segment Reporting Information [Line Items]
Premiums										0	0	0
Operating Segments | Specialty | Other Businesses
Segment Reporting Information [Line Items]
Premiums										0	0	0
Operating Segments | Military Services | Retail
Segment Reporting Information [Line Items]
Premiums										0	0	0
Operating Segments | Military Services | Employer Group
Segment Reporting Information [Line Items]
Premiums										0	0	0
Operating Segments | Military Services | Healthcare Services
Segment Reporting Information [Line Items]
Premiums										0	0	0
Operating Segments | Military Services | Other Businesses
Segment Reporting Information [Line Items]
Premiums										25	1,017	3,616
Operating Segments | Medicaid And Other | Retail
Segment Reporting Information [Line Items]
Premiums										328	185	176
Operating Segments | Medicaid And Other | Employer Group
Segment Reporting Information [Line Items]
Premiums										0	0	0
Operating Segments | Medicaid And Other | Healthcare Services
Segment Reporting Information [Line Items]
Premiums										0	0	0
Operating Segments | Medicaid And Other | Other Businesses
Segment Reporting Information [Line Items]
Premiums										670	853	782
Operating Segments | Provider | Retail
Segment Reporting Information [Line Items]
Services										0	0	0
Operating Segments | Provider | Employer Group
Segment Reporting Information [Line Items]
Services										19	12	0
Operating Segments | Provider | Healthcare Services
Segment Reporting Information [Line Items]
Services										1,223	1,008	892
Operating Segments | Provider | Other Businesses
Segment Reporting Information [Line Items]
Services										0	0	0
Operating Segments | Aso And Other | Retail
Segment Reporting Information [Line Items]
Services										16	24	16
Operating Segments | Aso And Other | Employer Group
Segment Reporting Information [Line Items]
Services										338	358	356
Operating Segments | Aso And Other | Healthcare Services
Segment Reporting Information [Line Items]
Services										0	0	0
Operating Segments | Aso And Other | Other Businesses
Segment Reporting Information [Line Items]
Services										454	308	85
Operating Segments | Pharmacy | Retail
Segment Reporting Information [Line Items]
Services										0	0	0
Operating Segments | Pharmacy | Employer Group
Segment Reporting Information [Line Items]
Services										0	0	0
Operating Segments | Pharmacy | Healthcare Services
Segment Reporting Information [Line Items]
Services										59	16	11
Operating Segments | Pharmacy | Other Businesses
Segment Reporting Information [Line Items]
Services										0	0	0
Eliminations/Corporate
Segment Reporting Information [Line Items]
Premiums										0	0	0
Services										0	0	0
Total revenues-external customers										0	0	0
Investment income										200	212	188
Total revenues										(14,502)	(11,883)	(10,339)
Benefits										(409)	(336)	(289)
Operating costs										(14,123)	(11,653)	(10,102)
Depreciation and amortization										(70)	(27)	(26)
Total operating expenses										(14,602)	(12,016)	(10,417)
Income from operations										100	133	78
Interest expense										140	105	109
Income before income taxes										(40)	28	(31)
Eliminations/Corporate | Medicare Advantage
Segment Reporting Information [Line Items]
Premiums										0	0	0
Eliminations/Corporate | Medicare Stand Alone Prescription Drug Plan
Segment Reporting Information [Line Items]
Premiums										0	0	0
Eliminations/Corporate | Medicare
Segment Reporting Information [Line Items]
Premiums										0	0	0
Eliminations/Corporate | Fully-Insured
Segment Reporting Information [Line Items]
Premiums										0	0	0
Eliminations/Corporate | Specialty
Segment Reporting Information [Line Items]
Premiums										0	0	0
Eliminations/Corporate | Military Services
Segment Reporting Information [Line Items]
Premiums										0	0	0
Eliminations/Corporate | Medicaid And Other
Segment Reporting Information [Line Items]
Premiums										0	0	0
Eliminations/Corporate | Provider
Segment Reporting Information [Line Items]
Services										0	0	0
Eliminations/Corporate | Aso And Other
Segment Reporting Information [Line Items]
Services										0	0	0
Eliminations/Corporate | Pharmacy
Segment Reporting Information [Line Items]
Services										$ 0	$ 0	$ 0

[1] The sum of quarterly amounts does not equal full year results due to the anti-dilutive impact of a loss in the fourth quarter. The fourth quarter includes an expense of $243 million ($154 million after tax, or $0.99 per diluted common share) for reserve strengthening associated with our closed block of long-term care insurance policies.