Consolidated Statement of Condition (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets, Current [Abstract]
Allowance for credit losses on all HTM investment securities	$ 1
Investment securities held-to-maturity under money market liquidity facility, fair value	4,841
Allowance for credit losses on HTM investment securities excluding MMF	2
Investment securities held-to-maturity	46,510	$ 42,157
Loans, allowance for credit losses	134	74
Premises and equipment, accumulated depreciation	$ 4,744	$ 4,367
Stockholders' Equity Attributable to Parent [Abstract]
Preferred stock, no par value (in USD per share)	$ 0	$ 0
Preferred stock, shares 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)	352,797,695	357,389,416
Treasury stock, shares (in shares)	151,081,947	146,490,226
Series C 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 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)	7,500	7,500
Preferred stock, shares outstanding (in shares)	7,500	7,500
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