Business Changes and Developments Preferred Stock Issuances (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended		6 Months Ended
	Jul. 29, 2015	Apr. 02, 2015	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2015	Jun. 30, 2014
Class of Stock [Line Items]
Trust preferred securities redeemed		$ 1,500
Common stock, dividends, per share (in dollars per share)					$ 0.84	$ 0.78
Preferred stock
Class of Stock [Line Items]
Issuance of preferred stock			$ 3,400		$ 4,855	$ 7,305
Preferred stock | Subsequent event
Class of Stock [Line Items]
Issuance of preferred stock	$ 1,200
Common stock
Class of Stock [Line Items]
Common stock, dividends, per share (in dollars per share)			$ 0.44	$ 0.40