Divestitures (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2011	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2011
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Purchase Price for Divestiture of Business	$ 1,500
Proceeds from Divestiture of Businesses			$ 30	$ 10	$ 1,450
Gain on divestitures		$ 0	12	38
Segment Reporting, Sales from Divested Businesses		$ 0	$ 4	$ 58