Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Stock, at cost [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Beginning Balance (in shares) at Dec. 31, 2012		1,488
Beginning Balance at Dec. 31, 2012	$ 865	$ 15	$ 3,881	$ 8,554	$ (4,024)	$ 298	$ 9,589
Net income				1,071			1,071
Other comprehensive income (loss), net of tax						(289)	(289)
Dividends declared on preferred stock				(57)			(57)
Dividends declared on common stock				(311)			(311)
Stock option exercises and other			(54)		314		260
Stock-based compensation and related tax effects			119				119
Other	4		5	(4)	(6)		(1)
Ending Balance at Dec. 31, 2013	869	$ 15	3,951	9,253	(3,716)	9	10,381
Ending Balance (in shares) at Dec. 31, 2013		1,488
Net income				1,321			1,321
Other comprehensive income (loss), net of tax						156	156
Dividends declared on preferred stock				(57)			(57)
Dividends declared on common stock				(316)			(316)
Stock option exercises and other			(53)		240		187
Stock-based compensation and related tax effects			139				139
Other	3		13	(3)	(21)		(8)
Ending Balance at Dec. 31, 2014	872	$ 15	4,050	10,198	(3,497)	165	11,803
Ending Balance (in shares) at Dec. 31, 2014		1,488
Net income				1,447			1,447
Other comprehensive income (loss), net of tax						(299)	(299)
Issuance of preferred stock	581						581
Dividends declared on preferred stock				(69)			(69)
Dividends declared on common stock				(318)			(318)
Stock option exercises and other			(87)		177		90
Stock-based compensation and related tax effects			172				172
Other	6		17	(5)	(23)		(5)
Ending Balance at Dec. 31, 2015	$ 1,459	$ 15	$ 4,152	$ 11,253	$ (3,343)	$ (134)	$ 13,402
Ending Balance (in shares) at Dec. 31, 2015		1,488