Basis of Presentation, Uses of Estimates and Significant Accounting Policies Medicare Part D (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Other current receivables	$ 6,801	$ 5,498
Other policy liabilities	7,798	5,965
CMS Subsidies [Member]
Other current receivables	1,703	1,801
Other policy liabilities	0	0
Drug Discount [Member]
Other current receivables	423	719
Other policy liabilities	58	302
Risk-Share [Member]
Other current receivables	0	20
Other policy liabilities	$ 496	$ 0