Business Segment Information (Business Segment Financial Results) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Net interest income (expense)		$ 545	$ 546	$ 500	$ 470	$ 455	$ 450	$ 445	$ 447	$ 2,061		$ 1,797	$ 1,689
Provision for credit losses										74		248	147
Noninterest income										1,107		1,051	1,035
Noninterest expenses		483	463	457	457	461	493	518	458	1,860		1,930	1,827
Provision (benefit) for income taxes		(218)	(108)	(99)	(66)	(62)	(64)	(42)	(25)	(491)		(193)	(229)
Net income (loss)		$ 112	$ 226	$ 203	$ 202	$ 164	$ 149	$ 104	$ 60	743		477	521
Net loan charge-offs (recoveries)										92		157	101
Assets, average										71,452		71,743	70,247
Loans, average										48,558		48,996	48,628
Deposits, average										$ 57,258		$ 57,741	$ 58,326
Return on average assets	[1],[2]									1.04%		0.67%	0.74%
Efficiency ratio	[3],[4]									58.57%		67.53%	66.93%
Remeasurement of deferred taxes as a result of the enactment of the Tax Cuts and Jobs Act										$ (107)		$ 0	$ 0
Income tax benefit related to employee stock transactions										(35)		0	0
Business Bank
Net interest income (expense)										1,372		1,417	1,497
Provision for credit losses										58		217	158
Noninterest income										601		572	571
Noninterest expenses										802		839	778
Provision (benefit) for income taxes										(389)		(295)	(371)
Net income (loss)										724		638	761
Net loan charge-offs (recoveries)										82		145	89
Assets, average										38,801		39,497	39,501
Loans, average										37,445		38,067	37,889
Deposits, average										$ 28,803		$ 29,704	$ 30,894
Return on average assets	[1]									1.87%		1.61%	1.93%
Efficiency ratio	[3]									40.61%		42.11%	37.59%
Retail Bank
Net interest income (expense)										$ 658		$ 618	$ 623
Provision for credit losses										13		35	8
Noninterest income										193		189	185
Noninterest expenses										731		767	734
Provision (benefit) for income taxes										(39)		(1)	(21)
Net income (loss)										68		4	45
Net loan charge-offs (recoveries)										15		12	29
Assets, average										6,478		6,551	6,474
Loans, average										5,857		5,881	5,792
Deposits, average										$ 23,971		$ 23,558	$ 22,876
Return on average assets	[1]									0.28%		0.02%	0.19%
Efficiency ratio	[3]									85.54%		94.35%	90.64%
Wealth Management
Net interest income (expense)										$ 170		$ 167	$ 177
Provision for credit losses										1		(4)	(20)
Noninterest income										255		243	235
Noninterest expenses										285		301	305
Provision (benefit) for income taxes										(51)		(39)	(43)
Net income (loss)										88		74	84
Net loan charge-offs (recoveries)										(5)		0	(17)
Assets, average										5,401		5,232	5,153
Loans, average										5,256		5,048	4,953
Deposits, average										$ 4,081		$ 4,126	$ 4,151
Return on average assets	[1]									1.63%		1.42%	1.62%
Efficiency ratio	[3]									66.84%		73.48%	73.68%
Finance
Net interest income (expense)										$ (175)		$ (428)	$ (623)
Provision for credit losses										0		0	0
Noninterest income										48		43	44
Noninterest expenses										(4)		(4)	(4)
Provision (benefit) for income taxes										58		142	206
Net income (loss)										(65)		(239)	(369)
Net loan charge-offs (recoveries)										0		0	0
Assets, average										13,954		13,993	11,764
Loans, average										0		0	0
Deposits, average										241		88	138
Other
Net interest income (expense)										36		23	15
Provision for credit losses										2		0	1
Noninterest income										10		4	0
Noninterest expenses										46		27	14
Provision (benefit) for income taxes										(70)	[5]	0	0
Net income (loss)										(72)		0	0
Net loan charge-offs (recoveries)										0		0	0
Assets, average										6,818		6,470	7,355
Loans, average										0		0	(6)
Deposits, average										162		265	267
Accounting Standards Update 2018-01 | Other
Remeasurement of deferred taxes as a result of the enactment of the Tax Cuts and Jobs Act										(107)
Accounting Standards Update 2016-09
Income tax benefit related to employee stock transactions										35		$ 4	$ 3
Accounting Standards Update 2016-09 | Other
Income tax benefit related to employee stock transactions										$ 35

[1] Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.

[2] Return on average assets is calculated based on the greater of average assets or average liabilities and attributed equity.

[3] Noninterest expenses as a percentage of the sum of net interest income (fully taxable equivalent basis) and noninterest income excluding net securities gains.

[4] Noninterest expenses as a percentage of the sum of net interest income (fully taxable equivalent basis) and noninterest income excluding net securities gains.

[5] Included a $107 million charge to adjust deferred taxes as a result of the enactment of the Tax Cuts and Jobs Act and a $35 million tax benefit from employee stock transactions.