Basis of Presentation, Use of Estimates and Significant Accounting Policies Basis of Presentation, Use of Estimates and Significant Accounting Policies Medicare Part D (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Other Receivables, Net, Current	$ 3,998	$ 2,889
Other Policyholder Funds	5,279	4,910
CMS Subsidies [Member]
Other Receivables, Net, Current	881	461
Other Policyholder Funds	0	0
Drug Discount [Member]
Other Receivables, Net, Current	425	314
Other Policyholder Funds	152	319
Risk-Share [Member]
Other Receivables, Net, Current	0	0
Other Policyholder Funds	$ 214	$ 438