Loans and Related Allowance for Credit Losses (Rollforward of Allowance for Credit Losses of Loans and Leases) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 4,868	$ 5,361
Charge-offs	(251)	(243)
Recoveries	114	97
Net (charge-offs)	(137)	(146)
Provision for (recapture of) credit losses	(172)	(502)
Other	(1)	1
Ending balance	4,558	4,714
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	662	584
Provision for (recapture of) credit losses	(23)	(77)
Ending balance	639	507
Allowance for credit loss	5,197	5,221
Allowances for investment securities and other financial assets	158	136
Total commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	3,185	3,337
Charge-offs	(52)	(69)
Recoveries	34	18
Net (charge-offs)	(18)	(51)
Provision for (recapture of) credit losses	(163)	(204)
Other	(1)	1
Ending balance	3,003	3,083
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	564	485
Provision for (recapture of) credit losses	23	(82)
Ending balance	587	403
Allowance for credit loss	3,590	3,486
Total consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	1,683	2,024
Charge-offs	(199)	(174)
Recoveries	80	79
Net (charge-offs)	(119)	(95)
Provision for (recapture of) credit losses	(9)	(298)
Ending balance	1,555	1,631
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Beginning balance	98	99
Provision for (recapture of) credit losses	(46)	5
Ending balance	52	104
Allowance for credit loss	$ 1,607	$ 1,735