Shareholders' Equity - Common Stock Repurchase Summary (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Total purchase price of shares repurchased and retired	$ 7,025	$ 28,144	$ 20,094
Common Stock
Class of Stock [Line Items]
Total number of shares repurchased and retired (in shares)	227	956	676
Total purchase price of shares repurchased and retired	$ 7,025	$ 28,144	$ 20,094
Common Stock | CCAR capital plan repurchases
Class of Stock [Line Items]
Total purchase price of shares repurchased and retired	7,025	25,644	16,754
Common Stock | Other authorized repurchases
Class of Stock [Line Items]
Total purchase price of shares repurchased and retired	$ 0	$ 2,500	$ 3,340