Goodwill, Other Intangibles, and Property and Equipment - Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 5,989	$ 6,029
Goodwill acquired	0
Impact of foreign currency translation	(44)	(43)
Goodwill, Ending Balance	6,019	5,989
QualCare Alliance Networks, Inc. [Member]
Goodwill [Line Items]
Goodwill acquired	74	0
Other [Member]
Goodwill [Line Items]
Goodwill acquired		$ 3
Global Health Care [Member]
Goodwill [Line Items]
Goodwill, Ending Balance	5,700
Global Supplemental Benefits [Member]
Goodwill [Line Items]
Goodwill, Ending Balance	$ 300