Basis of Presentation (Details) - USD ($) $ in Millions	Jan. 01, 2020	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses			$ 14,300
Allowance for credit losses reclassified		$ 23,244	13,123	$ 13,533	$ 13,445
CECL adoption impact
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses	$ 4,300
Balance sheet reclassification	(800)
Total pre-tax impact	3,500
Tax effect	(800)
Decrease to retained earnings	2,700
Allowance for credit losses reclassified			4,172
Pre-CECL adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses	18,600
Consumer, excluding credit card
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses			2,600
Allowance for credit losses reclassified		3,454	2,538	3,399	3,434
Consumer, excluding credit card | Reclassification Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses reclassified			600
Consumer, excluding credit card | CECL adoption impact
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses	400
Allowance for credit losses reclassified			297
Consumer, excluding credit card | CECL adoption impact | Reclassification Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses reclassified	(200)
Consumer, excluding credit card | Pre-CECL adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses	3,000
Credit card
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses			5,700
Credit card | CECL adoption impact
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses	5,500
Credit card | Pre-CECL adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses	11,200
Wholesale
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses			6,000
Allowance for credit losses reclassified		$ 4,840	4,902	$ 4,951	$ 4,827
Wholesale | CECL adoption impact
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses	(1,600)
Allowance for credit losses reclassified			$ (1,642)
Wholesale | Pre-CECL adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses	$ 4,400