Total Equity (Preferred Stock) (Details) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
	Mar. 19, 2015 USD ($) $ / shares shares	Sep. 30, 2015 USD ($) shares	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) shares	Sep. 30, 2014 USD ($)
Preferred Stock
Proceeds from issuance of preferred stock, net of issuance costs				$ 1,493	$ 2,782
Preferred stock shares authorized | shares		30,000,000		30,000,000
Dividends declared, Preferred Stock		$ 78	$ 62	$ 297	$ 192
Series J Preferred Stock
Preferred Stock
Preferred stock issuance date	Mar. 19, 2015
Depositary Shares issued (in shares) | shares	1,500,000
Depositary Shares issued	$ 1,500
Fraction of underlying stock that each Depositary Share represents	0.04
Preferred stock par value (per share) | $ / shares	$ 0.01
Preferred stock redemption price (per share) | $ / shares	25,000
Preferred stock redemption price per Depositary Share | $ / shares	$ 1,000
Proceeds from issuance of preferred stock, net of issuance costs	$ 1,493
Preferred stock redemption terms	The Series J Preferred Stock is redeemable at the Company’s option, (i) in whole or in part, from time to time, on any dividend payment date on or after July 15, 2020 or (ii) in whole but not in part at any time within 90 days following a regulatory capital treatment event (as described in the terms of that series), in each case at a redemption price of $25,000 per share (equivalent to $1,000 per Depositary Share), plus any declared and unpaid dividends up to, but excluding, the date fixed for redemption, without accumulation of any undeclared dividends.