Earnings Per Share (Details) - USD ($) shares in Millions, $ in Millions			1 Months Ended	3 Months Ended	12 Months Ended
	May. 27, 2015	May. 26, 2015	Jan. 31, 2016	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2015	Oct. 20, 2014	Feb. 15, 2013
Anti-dilutive securities excluded from the computation of earnings per common share
Anti-dilutive securities excluded from the computation of earnings per common share (in shares)				36
Amount authorized under stock repurchase program								$ 5,000	$ 5,000	$ 1,500
Payment for shares repurchased on the open market			$ 300		$ 2,800	$ 550	$ 223
Shares repurchased					46	9	4
Earnings allocable to participating securities - Basic (in dollars)					$ 26	$ 9	$ 26
Earnings allocable to participating securities - Diluted (in dollars)					$ 26	$ 9	$ 26
Morgan Stanley & Co. LLC
Anti-dilutive securities excluded from the computation of earnings per common share
Amount authorized under stock repurchase program		$ 5,000
Payment for shares repurchased on the open market		$ 5,000
Shares repurchased	68	5
Percentage of initial delivery of shares		90.00%
Restricted Stock And Restricted Stock Units
Anti-dilutive securities excluded from the computation of earnings per common share
Anti-dilutive securities excluded from the computation of earnings per common share (in shares)					4	4	5