Supplemental Disclosures (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock-based compensation expense, equity awards	$ 67	$ 75	$ 110
Non-cash issuance of common stock	72	108	150
Deferred purchase consideration from prior years' acquisitions	36	$ 25	$ 15
Putnam
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash used in operating activities, discontinued operations	$ 82