Amounts Associated With 3Rs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Supplementary Insurance Information, by Segment [Line Items]
Other current assets	$ 16,975		$ 16,975		$ 15,536
Trade accounts payable and accrued expenses	(3,292)		(3,292)		(2,095)
Other long-term assets	2,005		2,005		1,583
Other long-term liabilities	(357)		(357)		(236)
Risk Adjustment Settlement
Supplementary Insurance Information, by Segment [Line Items]
Premiums receivable	44		44		131
Other current assets	0		0		0
Trade accounts payable and accrued expenses	(169)		(169)		(89)
Net current (liability) asset	(125)		(125)		42
Other long-term assets	65		65		0
Other long-term liabilities	(106)		(106)		0
Net long-term (liability) asset	(41)		(41)		0
Total net asset	(166)		(166)		42
Reinsurance Recoverables
Supplementary Insurance Information, by Segment [Line Items]
Premiums receivable	0		0		0
Other current assets	521		521		586
Trade accounts payable and accrued expenses	0		0		0
Net current (liability) asset	521		521		586
Other long-term assets	168		168		0
Other long-term liabilities	0		0		0
Net long-term (liability) asset	168		168		0
Total net asset	689		689		586
Risk Corridor Settlement
Supplementary Insurance Information, by Segment [Line Items]
Premiums receivable	0		0		0
Other current assets	243		243		55
Trade accounts payable and accrued expenses	0		0		(4)
Net current (liability) asset	243		243		51
Other long-term assets	133		133		0
Other long-term liabilities	0		0		0
Net long-term (liability) asset	133		133		0
Total net asset	376		376		$ 51
Health Care Reform
Supplementary Insurance Information, by Segment [Line Items]
Decline in the estimated net receivable	(29)		(40)
Expected payment of annual health insurance industry fee	866		866
Amortization of deferred charges	213	$ 143	433	$ 280
Deferred costs	$ 433		$ 433