Medical Cost and Medical Costs Payable Medical Costs and Medical Costs Payable Rollforward (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Medical costs payable, beginning of period	$ 11,004	$ 9,799	$ 9,220
Acquisitions	0	1,029	155
Current year	89,970	81,086	75,052
Prior years	(680)	(860)	(720)
Total reported medical costs	89,290	80,226	74,332
Payments for current year	(78,989)	(71,832)	(65,763)
Payments for prior year	(9,730)	(8,218)	(8,145)
Total claim payments	(88,719)	(80,050)	(73,908)
Medical costs payable, end of period	$ 11,575	$ 11,004	$ 9,799