Total Equity and Other Comprehensive Income (Rollforward of Total Equity) (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended									9 Months Ended						9 Months Ended					9 Months Ended				9 Months Ended						9 Months Ended				9 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014 Cumulative effect of adopting ASC 860-50 [Member]	Sep. 30, 2014 Cumulative effect of adopting ASU 2014-01 [Member]	Sep. 30, 2013 Cumulative effect of adopting ASU 2014-01 [Member]	Sep. 30, 2014 Cumulative effect of adopting ASU 2014-01 [Member] Cumulative effect of adopting ASC 860-50 [Member]	Dec. 31, 2013 Cumulative effect of adopting ASU 2014-01 [Member] Cumulative effect of adopting ASC 860-50 [Member]	Sep. 30, 2013 Series L Preferred Stock [Member]	Sep. 30, 2013 Series R Preferred Stock [Member]	Sep. 30, 2014 Common Stock [Member]	Sep. 30, 2013 Common Stock [Member]	Sep. 30, 2013 Common Stock [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Sep. 30, 2014 Common Stock [Member] Cumulative effect of adopting ASU 2014-01 [Member] Cumulative effect of adopting ASC 860-50 [Member]	Sep. 30, 2014 Preferred Stock Including Additional Paid in Capital [Member]	Sep. 30, 2013 Preferred Stock Including Additional Paid in Capital [Member]	Sep. 30, 2013 Preferred Stock Including Additional Paid in Capital [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Sep. 30, 2014 Preferred Stock Including Additional Paid in Capital [Member] Cumulative effect of adopting ASU 2014-01 [Member] Cumulative effect of adopting ASC 860-50 [Member]	Sep. 30, 2013 Preferred Stock Including Additional Paid in Capital [Member] Series L Preferred Stock [Member]	Sep. 30, 2013 Preferred Stock Including Additional Paid in Capital [Member] Series R Preferred Stock [Member]	Sep. 30, 2014 Common Stock Including Additional Paid in Capital [Member]	Sep. 30, 2013 Common Stock Including Additional Paid in Capital [Member]	Sep. 30, 2013 Common Stock Including Additional Paid in Capital [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Sep. 30, 2014 Retained Earnings [Member]	Sep. 30, 2013 Retained Earnings [Member]	Sep. 30, 2014 Retained Earnings [Member] Cumulative effect of adopting ASC 860-50 [Member]	Sep. 30, 2014 Retained Earnings [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Sep. 30, 2013 Retained Earnings [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Sep. 30, 2014 Retained Earnings [Member] Cumulative effect of adopting ASU 2014-01 [Member] Cumulative effect of adopting ASC 860-50 [Member]	Sep. 30, 2014 Accumulated Other Comprehensive Income (Loss) [Member]	Sep. 30, 2013 Accumulated Other Comprehensive Income (Loss) [Member]	Sep. 30, 2013 Accumulated Other Comprehensive Income (Loss) [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Sep. 30, 2014 Accumulated Other Comprehensive Income (Loss) [Member] Cumulative effect of adopting ASU 2014-01 [Member] Cumulative effect of adopting ASC 860-50 [Member]	Sep. 30, 2014 Treasury Stock [Member]	Sep. 30, 2013 Treasury Stock [Member]	Sep. 30, 2013 Treasury Stock [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Sep. 30, 2014 Treasury Stock [Member] Cumulative effect of adopting ASU 2014-01 [Member] Cumulative effect of adopting ASC 860-50 [Member]	Sep. 30, 2014 Noncontrolling Interest [Member]	Sep. 30, 2013 Noncontrolling Interest [Member]	Sep. 30, 2014 Noncontrolling Interest [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Sep. 30, 2013 Noncontrolling Interest [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Sep. 30, 2014 Noncontrolling Interest [Member] Cumulative effect of adopting ASU 2014-01 [Member] Cumulative effect of adopting ASC 860-50 [Member]
Common Stock [Abstract]
Beginning Balance (in shares)																533	528	528	533
Common stock activity, shares																1	1
Treasury stock activity, shares																(6)	3
Ending Balance, (in shares)																528	532	528	533
Common Stock, Beginning Balance					$ 2,698,000,000											$ 2,698,000,000	$ 2,690,000,000	$ 2,690,000,000	$ 2,698,000,000
Capital surplus - Preferred Stock, Beginning Balance					3,941,000,000															3,941,000,000	3,590,000,000	3,590,000,000	3,941,000,000
Capital surplus - Common Stock, Beginning Balance					12,416,000,000														12,416,000,000							12,416,000,000	12,193,000,000	12,193,000,000
Retained Earnings, Beginning Balance					23,251,000,000	[1]																							23,325,000,000	20,265,000,000			20,210,000,000	23,253,000,000
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance					436,000,000																														436,000,000	834,000,000	834,000,000	436,000,000
Treasury Stock, Beginning Balance					408,000,000																																		(408,000,000)	(569,000,000)	(569,000,000)	(408,000,000)
Noncontrolling interests, Beginning Balance					1,703,000,000	[1]																																					1,689,000,000	2,762,000,000		2,772,000,000	1,703,000,000
Total Equity, Beginning Balance					44,037,000,000		41,765,000,000				41,720,000,000	44,039,000,000	44,097,000,000
Net income	1,038,000,000	[1]	1,028,000,000	[1]	3,150,000,000	[1]	3,138,000,000	[1]																					3,148,000,000	3,140,000,000													2,000,000	(2,000,000)
Other comprehensive income (loss), net of tax	(154,000,000)		2,000,000		291,000,000		(787,000,000)																												291,000,000	(787,000,000)
Cash dividends declared [Abstract]
Common					(748,000,000)		(677,000,000)																						(748,000,000)	(677,000,000)
Preferred					(185,000,000)		(188,000,000)																						(185,000,000)	(188,000,000)
Preferred stock discount accretion																				4,000,000	4,000,000								(4,000,000)	(4,000,000)
Redemption of noncontrolling interests							(375,000,000)																							(7,000,000)														(368,000,000)
Common stock activity					61,000,000		69,000,000									5,000,000	5,000,000									56,000,000	64,000,000
Treasury stock activity					(511,000,000)		97,000,000																			12,000,000	(49,000,000)												(523,000,000)	146,000,000
Other					(102,000,000)		(596,000,000)																			89,000,000	102,000,000																(191,000,000)	(698,000,000)
Common Stock, Ending Balance	2,703,000,000				2,703,000,000											2,703,000,000	2,695,000,000	2,690,000,000	2,698,000,000
Capital surplus - Preferred Stock, Ending Balance	3,945,000,000				3,945,000,000															3,945,000,000	3,940,000,000	3,590,000,000	3,941,000,000
Capital surplus - Common Stock, Ending Balance	12,573,000,000				12,573,000,000														12,416,000,000							12,573,000,000	12,310,000,000	12,193,000,000
Retained Earnings, Ending Balance	25,464,000,000	[1]			25,464,000,000	[1]																							25,464,000,000	22,474,000,000			20,210,000,000	23,253,000,000
Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance	727,000,000				727,000,000																														727,000,000	47,000,000	834,000,000	436,000,000
Treasury Stock, Ending Balance	931,000,000				931,000,000																																		(931,000,000)	(423,000,000)	(569,000,000)	(408,000,000)
Noncontrolling interests, Ending Balance	1,514,000,000	[1]			1,514,000,000	[1]																																					1,514,000,000	1,704,000,000		2,772,000,000	1,703,000,000
Total Equity, Ending Balance	45,995,000,000		42,747,000,000		45,995,000,000		42,747,000,000				41,720,000,000	44,039,000,000	44,097,000,000
Cumulative effect adjustment									2,000,000	(60,000,000)	(45,000,000)																				2,000,000	(74,000,000)	(55,000,000)												14,000,000	10,000,000
Common Stock Per Share Dividends Declared					$ 1.4		$ 1.28
Preferred stock redemption, shares														1,500
Preferred stock redemption, value														(150,000,000)										(150,000,000)
Preferred stock issuance, shares															5,000
Preferred stock issuance, value							$ 496,000,000								$ 496,000,000										$ 496,000,000

[1] Amounts for 2013 periods have been updated to reflect the first quarter 2014 adoption of Accounting Standards Update (ASU) 2014-01 related to investments in low income housing tax credits.