Medical Costs and Medical Costs Payable Medical Costs And Medical Costs Payable (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Medical Cost and Medical Cost Payable [Roll Forward]
Medical costs payable, beginning of period	$ 9,220	$ 9,362	$ 8,664
Acquisitions	155	0	252
Reported Medical costs, current year	75,052	69,641	65,599
Reported medical costs, prior years	(720)	(800)	(310)
Medical costs	74,332	68,841	65,289
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	74,332	68,841	65,289
Claim payments, current year	(65,763)	(60,949)	(57,109)
Claim payments, prior year	(8,145)	(8,034)	(7,734)
Total claim payments	(73,908)	(68,983)	(64,843)
Medical costs payable, end of period	$ 9,799	$ 9,220	$ 9,362