Total Equity and Other Comprehensive Income (Rollforward of Total Equity) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended									6 Months Ended						6 Months Ended					6 Months Ended				6 Months Ended						6 Months Ended				6 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014 Cumulative effect of adopting ASC 860-50 [Member]	Jun. 30, 2014 Cumulative effect of adopting ASU 2014-01 [Member]	Jun. 30, 2013 Cumulative effect of adopting ASU 2014-01 [Member]	Jun. 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]	Jun. 30, 2013 Series L Preferred Stock [Member]	Jun. 30, 2013 Series R Preferred Stock [Member]	Jun. 30, 2014 Common Stock [Member]	Jun. 30, 2013 Common Stock [Member]	Jun. 30, 2013 Common Stock [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Jun. 30, 2014 Common Stock [Member] Cumulative effect of adopting ASU 2014-01 [Member] Cumulative effect of adopting ASC 860-50 [Member]	Jun. 30, 2014 Preferred Stock Including Additional Paid in Capital [Member]	Jun. 30, 2013 Preferred Stock Including Additional Paid in Capital [Member]	Jun. 30, 2013 Preferred Stock Including Additional Paid in Capital [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Jun. 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]	Jun. 30, 2013 Preferred Stock Including Additional Paid in Capital [Member] Series L Preferred Stock [Member]	Jun. 30, 2013 Preferred Stock Including Additional Paid in Capital [Member] Series R Preferred Stock [Member]	Jun. 30, 2014 Common Stock Including Additional Paid in Capital [Member]	Jun. 30, 2013 Common Stock Including Additional Paid in Capital [Member]	Jun. 30, 2013 Common Stock Including Additional Paid in Capital [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Jun. 30, 2014 Retained Earnings [Member]	Jun. 30, 2013 Retained Earnings [Member]	Jun. 30, 2014 Retained Earnings [Member] Cumulative effect of adopting ASC 860-50 [Member]	Jun. 30, 2014 Retained Earnings [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Jun. 30, 2013 Retained Earnings [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Jun. 30, 2014 Retained Earnings [Member] Cumulative effect of adopting ASU 2014-01 [Member] Cumulative effect of adopting ASC 860-50 [Member]	Jun. 30, 2014 Accumulated Other Comprehensive Income (Loss) [Member]	Jun. 30, 2013 Accumulated Other Comprehensive Income (Loss) [Member]	Jun. 30, 2013 Accumulated Other Comprehensive Income (Loss) [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Jun. 30, 2014 Accumulated Other Comprehensive Income (Loss) [Member] Cumulative effect of adopting ASU 2014-01 [Member] Cumulative effect of adopting ASC 860-50 [Member]	Jun. 30, 2014 Treasury Stock [Member]	Jun. 30, 2013 Treasury Stock [Member]	Jun. 30, 2013 Treasury Stock [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Jun. 30, 2014 Treasury Stock [Member] Cumulative effect of adopting ASU 2014-01 [Member] Cumulative effect of adopting ASC 860-50 [Member]	Jun. 30, 2014 Noncontrolling Interest [Member]	Jun. 30, 2013 Noncontrolling Interest [Member]	Jun. 30, 2014 Noncontrolling Interest [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Jun. 30, 2013 Noncontrolling Interest [Member] Cumulative effect of adopting ASU 2014-01 [Member]	Jun. 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																(2)	2
Ending Balance, (in shares)																532	531	528	533
Common Stock, Beginning Balance					$ 2,698											$ 2,698	$ 2,690	$ 2,690	$ 2,698
Capital surplus - Preferred Stock, Beginning Balance					3,941															3,941	3,590	3,590	3,941
Capital surplus - Common Stock, Beginning Balance					12,416														12,416							12,416	12,193	12,193
Retained Earnings, Beginning Balance					23,251	[1]																							23,325	20,265			20,210	23,253
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance					436																														436	834	834	436
Treasury Stock, Beginning Balance					408																																		(408)	(569)	(569)	(408)
Noncontrolling interests, Beginning Balance					1,703	[1]																																					1,689	2,762		2,772	1,703
Total Equity, Beginning Balance					44,037		41,765				41,720	44,039	44,097
Net income	1,052	[1]	1,115	[1]	2,112	[1]	2,110	[1]																					2,111	2,114													1	(4)
Other comprehensive income (loss), net of tax	225		(722)		445		(789)																												445	(789)
Cash dividends declared [Abstract]
Common					(491)		(444)																						(491)	(444)
Preferred					(115)		(118)																						(115)	(118)
Preferred stock discount accretion																				3	3								(3)	(3)
Redemption of noncontrolling interests							(375)																							(7)														(368)
Common stock activity					60		35									5	3									55	32
Treasury stock activity					(165)		74																			11	(42)												(176)	116
Other					(92)		(682)																			24	51																(116)	(733)
Common Stock, Ending Balance	2,703				2,703											2,703	2,693	2,690	2,698
Capital surplus - Preferred Stock, Ending Balance	3,944				3,944															3,944	3,939	3,590	3,941
Capital surplus - Common Stock, Ending Balance	12,506				12,506														12,416							12,506	12,234	12,193
Retained Earnings, Ending Balance	24,755	[1]			24,755	[1]																							24,755	21,752			20,210	23,253
Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance	881				881																														881	45	834	436
Treasury Stock, Ending Balance	584				584																																		(584)	(453)	(569)	(408)
Noncontrolling interests, Ending Balance	1,588	[1]			1,588	[1]																																					1,588	1,667		2,772	1,703
Total Equity, Ending Balance	45,793		41,877		45,793		41,877				41,720	44,039	44,097
Cumulative effect adjustment									2	(60)	(45)																				2	(74)	(55)												14	10
Common Stock Per Share Dividends Declared					$ 0.92		$ 0.84
Preferred stock redemption, shares														1,500
Preferred stock redemption, value														(150)										(150)
Preferred stock issuance, shares															5,000
Preferred stock issuance, value							$ 496								$ 496										$ 496

[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.