Consolidated Statement of Changes in Equity - USD ($)		Total	Series L Preferred Stock [Member]	Series K Preferred Stock [Member]	Common Stock [Member]	Preferred Stock Including Additional Paid in Capital [Member]	Preferred Stock Including Additional Paid in Capital [Member] Series L Preferred Stock [Member]	Preferred Stock Including Additional Paid in Capital [Member] Series R Preferred Stock [Member]	Preferred Stock Including Additional Paid in Capital [Member] Series K Preferred Stock [Member]	Common Stock Including Additional Paid in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]		Treasury Stock [Member]	Noncontrolling Interest [Member]
Beginning Balance (in shares) at Dec. 31, 2012	[1]				528,000,000
Common Stock, Beginning Balance at Dec. 31, 2012	[1]				$ 2,690,000,000
Capital surplus - Preferred Stock, Beginning Balance at Dec. 31, 2012	[1]					$ 3,590,000,000
Capital surplus - Common Stock, Beginning Balance at Dec. 31, 2012	[1]									$ 12,193,000,000
Retained Earnings, Beginning Balance at Dec. 31, 2012	[1]										$ 20,210,000,000
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance at Dec. 31, 2012		$ 834,000,000										$ 834,000,000	[1]
Treasury Stock, Beginning Balance at Dec. 31, 2012	[1]													$ (569,000,000)
Noncontrolling interests, Beginning Balance at Dec. 31, 2012	[1]														$ 2,772,000,000
Total Equity, Beginning Balance at Dec. 31, 2012		41,720,000,000
Cash dividends declared [Abstract]
Preferred stock redemption, shares			1,500
Beginning Balance (in shares) at Dec. 31, 2012	[1]				528,000,000
Common Stock [Abstract]
Common stock activity, shares					2,000,000
Treasury stock activity, shares					3,000,000
Ending Balance, (in shares) at Dec. 31, 2013					533,000,000
Ending Balance, (in shares) (Cumulative effect of adopting ASU 2014-01 [Member]) at Dec. 31, 2013					533,000,000
Common Stock, Beginning Balance at Dec. 31, 2012	[1]				$ 2,690,000,000
Capital surplus - Preferred Stock, Beginning Balance at Dec. 31, 2012	[1]					3,590,000,000
Capital surplus - Common Stock, Beginning Balance at Dec. 31, 2012	[1]									12,193,000,000
Retained Earnings, Beginning Balance at Dec. 31, 2012	[1]										20,210,000,000
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance at Dec. 31, 2012		834,000,000										834,000,000	[1]
Treasury Stock, Beginning Balance at Dec. 31, 2012	[1]													(569,000,000)
Noncontrolling interests, Beginning Balance at Dec. 31, 2012	[1]														2,772,000,000
Total Equity, Beginning Balance at Dec. 31, 2012		41,720,000,000
Common Stock [Abstract]
Net income		4,212,000,000									4,201,000,000				11,000,000
Other comprehensive income (loss), net of tax		(398,000,000)										(398,000,000)
Cash dividends declared [Abstract]
Common		(911,000,000)									(911,000,000)
Preferred		(237,000,000)									(237,000,000)
Preferred stock discount accretion						5,000,000					(5,000,000)
Redemption of noncontrolling interests		(375,000,000)									(7,000,000)				(368,000,000)
Common stock activity		105,000,000			8,000,000					97,000,000
Treasury stock activity		114,000,000								(47,000,000)				161,000,000
Other		(539,000,000)								173,000,000					(712,000,000)
Common Stock, Ending Balance at Dec. 31, 2013					2,698,000,000
Common Stock, Ending Balance (Cumulative effect of adopting ASU 2014-01 [Member]) at Dec. 31, 2013					$ 2,698,000,000
Capital surplus - Preferred Stock, Ending Balance at Dec. 31, 2013						3,941,000,000
Capital surplus - Preferred Stock, Ending Balance (Cumulative effect of adopting ASU 2014-01 [Member]) at Dec. 31, 2013						3,941,000,000
Capital surplus - Common Stock, Ending Balance at Dec. 31, 2013										12,416,000,000
Capital surplus - Common Stock, Ending Balance (Cumulative effect of adopting ASU 2014-01 [Member]) at Dec. 31, 2013										12,416,000,000
Retained Earnings, Ending Balance at Dec. 31, 2013											23,251,000,000
Retained Earnings, Ending Balance (Cumulative effect of adopting ASU 2014-01 [Member]) at Dec. 31, 2013											23,253,000,000
Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance at Dec. 31, 2013		436,000,000										436,000,000
Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance (Cumulative effect of adopting ASU 2014-01 [Member]) at Dec. 31, 2013												436,000,000
Treasury Stock, Ending Balance at Dec. 31, 2013														(408,000,000)
Treasury Stock, Ending Balance (Cumulative effect of adopting ASU 2014-01 [Member]) at Dec. 31, 2013														(408,000,000)
Noncontrolling interests, Ending Balance at Dec. 31, 2013															1,703,000,000
Noncontrolling interests, Ending Balance (Cumulative effect of adopting ASU 2014-01 [Member]) at Dec. 31, 2013															1,703,000,000
Total Equity, Ending Balance at Dec. 31, 2013		44,037,000,000
Total Equity, Ending Balance (Cumulative effect of adopting ASU 2014-01 [Member]) at Dec. 31, 2013		44,039,000,000
Cash dividends declared [Abstract]
Noncontrolling Interest Decrease From Deconsolidation		675,000,000
Preferred Stock, Par or Stated Value Per Share			$ 1
Cumulative effect adjustment		2,000,000									2,000,000
Preferred stock redemption, value		(150,000,000)					$ (150,000,000)
Preferred stock issued, value		496,000,000						$ 496,000,000
Common stock activity, shares					1,000,000
Treasury stock activity, shares					(11,000,000)
Ending Balance, (in shares) at Dec. 31, 2014					523,000,000
Common Stock [Abstract]
Net income		4,207,000,000									4,184,000,000				23,000,000
Other comprehensive income (loss), net of tax		67,000,000										67,000,000
Cash dividends declared [Abstract]
Common		(1,000,000,000)									(1,000,000,000)
Preferred		(232,000,000)									(232,000,000)
Preferred stock discount accretion						5,000,000					(5,000,000)
Common stock activity		88,000,000			$ 7,000,000					81,000,000
Treasury stock activity		(1,008,000,000)								14,000,000				(1,022,000,000)
Other	[2]	(87,000,000)								116,000,000					(203,000,000)
Common Stock, Ending Balance at Dec. 31, 2014		2,705,000,000			$ 2,705,000,000
Capital surplus - Preferred Stock, Ending Balance at Dec. 31, 2014		3,946,000,000				3,946,000,000
Capital surplus - Common Stock, Ending Balance at Dec. 31, 2014		12,627,000,000								12,627,000,000
Retained Earnings, Ending Balance at Dec. 31, 2014		26,200,000,000									26,200,000,000
Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance at Dec. 31, 2014		503,000,000										503,000,000
Treasury Stock, Ending Balance at Dec. 31, 2014		1,430,000,000												(1,430,000,000)
Noncontrolling interests, Ending Balance at Dec. 31, 2014		1,523,000,000													1,523,000,000
Total Equity, Ending Balance at Dec. 31, 2014		46,074,000,000
Cash dividends declared [Abstract]
Preferred stock redemption, value	[3]	0
Preferred stock issued, value	[4]	$ 0
Preferred Stock, Par or Stated Value Per Share		$ 1
Preferred stock redemption, shares				50,000
Beginning Balance (in shares) at Dec. 31, 2014					523,000,000
Common Stock [Abstract]
Common stock activity, shares					1,000,000
Treasury stock activity, shares					(20,000,000)
Ending Balance, (in shares) at Dec. 31, 2015					504,000,000
Common Stock, Beginning Balance at Dec. 31, 2014		$ 2,705,000,000			$ 2,705,000,000
Capital surplus - Preferred Stock, Beginning Balance at Dec. 31, 2014		3,946,000,000				3,946,000,000
Capital surplus - Common Stock, Beginning Balance at Dec. 31, 2014		12,627,000,000								12,627,000,000
Retained Earnings, Beginning Balance at Dec. 31, 2014		26,200,000,000									26,200,000,000
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance at Dec. 31, 2014		503,000,000										503,000,000
Treasury Stock, Beginning Balance at Dec. 31, 2014		1,430,000,000												(1,430,000,000)
Noncontrolling interests, Beginning Balance at Dec. 31, 2014		1,523,000,000													1,523,000,000
Total Equity, Beginning Balance at Dec. 31, 2014		46,074,000,000
Common Stock [Abstract]
Net income		4,143,000,000									4,106,000,000				37,000,000
Other comprehensive income (loss), net of tax		(373,000,000)										(373,000,000)
Cash dividends declared [Abstract]
Common		(1,038,000,000)									(1,038,000,000)
Preferred		(219,000,000)									(219,000,000)
Preferred stock discount accretion						6,000,000					(6,000,000)
Common stock activity		49,000,000			3,000,000					46,000,000
Treasury stock activity		(1,994,000,000)								(56,000,000)				(1,938,000,000)
Other		(162,000,000)								128,000,000					(290,000,000)
Common Stock, Ending Balance at Dec. 31, 2015		2,708,000,000			$ 2,708,000,000
Capital surplus - Preferred Stock, Ending Balance at Dec. 31, 2015		3,452,000,000				$ 3,452,000,000
Capital surplus - Common Stock, Ending Balance at Dec. 31, 2015		12,745,000,000								$ 12,745,000,000
Retained Earnings, Ending Balance at Dec. 31, 2015		29,043,000,000									$ 29,043,000,000
Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance at Dec. 31, 2015		130,000,000										$ 130,000,000
Treasury Stock, Ending Balance at Dec. 31, 2015		3,368,000,000												$ (3,368,000,000)
Noncontrolling interests, Ending Balance at Dec. 31, 2015		1,270,000,000													$ 1,270,000,000
Total Equity, Ending Balance at Dec. 31, 2015		45,980,000,000
Cash dividends declared [Abstract]
Depositary Shares				500,000
Preferred stock redemption, value		(500,000,000)							$ (500,000,000)
Preferred stock issued, value	[4]	$ 0
Preferred Stock, Par or Stated Value Per Share		$ 1

[1] The par value of our preferred stock outstanding was less than $.5 million at each date and, therefore, is excluded from this presentation.

[2] Includes an impact to noncontrolling interests for deconsolidation of limited partnership or non-managing member interests related to tax credit investments in the amount of $675 million during the second quarter of 2013.

[3] 1,500 Series L preferred shares with a $1 par value were redeemed on April 19, 2013.

[4] Par value less than $.5 million at each date.