Consolidated Statement of Condition (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Assets, Current [Abstract]
Allowance for credit losses on all HTM investment securities	$ 0	$ 1
Investment securities held-to-maturity under money market liquidity facility, fair value	0	3,304
Allowance for credit losses on HTM investment securities excluding MMF	2	2
Investment securities held-to-maturity	45,685	50,003
Allowance for credit loss	100	122
Accumulated depreciation	$ 5,108	$ 4,825
Stockholders' Equity Attributable to Parent [Abstract]
Preferred stock, no par value (in USD per share)	$ 0	$ 0
Preferred stock authorized (in shares)	3,500,000	3,500,000
Common stock, par value (usd per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	750,000,000	750,000,000
Common stock, shares issued (in shares)	503,879,642	503,879,642
Common stock, shares outstanding (in shares)	343,503,114	353,156,279
Treasury stock, shares (in shares)	160,376,528	150,723,363
Series D Preferred Stock
Stockholders' Equity Attributable to Parent [Abstract]
Preferred stock, shares issued (in shares)	7,500	7,500
Preferred stock, shares outstanding (in shares)	7,500	7,500
Series F Preferred Stock
Stockholders' Equity Attributable to Parent [Abstract]
Preferred stock, shares issued (in shares)	2,500	2,500
Preferred stock, shares outstanding (in shares)	2,500	2,500
Series G Preferred Stock
Stockholders' Equity Attributable to Parent [Abstract]
Preferred stock, shares issued (in shares)	5,000	5,000
Preferred stock, shares outstanding (in shares)	5,000	5,000
Series H Preferred Stock
Stockholders' Equity Attributable to Parent [Abstract]
Preferred stock, shares issued (in shares)	5,000	5,000
Preferred stock, shares outstanding (in shares)	5,000	5,000