Basis of Presentation, Uses of Estimates and Significant Accounting Policies Medicare Part D (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Other current receivables	$ 5,498	$ 3,998
Other policy liabilities	5,965	5,279
CMS Subsidies [Member]
Other current receivables	1,801	881
Other policy liabilities	0	0
Drug Discount [Member]
Other current receivables	719	425
Other policy liabilities	302	152
Risk-Share [Member]
Other current receivables	20	0
Other policy liabilities	$ 0	$ 214