Shareholders' Equity - Adjustments to Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Gains (losses) from sales of available-for-sale securities, net	$ 57	$ 4	$ (1)
Net interest income	1,905	2,200	2,566
Compensation and employee benefits expenses	4,554	4,450	4,541
Net income	2,693	2,420	$ 2,242
Net realized gains from sales of available-for-sale securities, taxes	(15)	0
Net realized gains from sales of available-for-sale securities, tax	25	20
Other comprehensive (income) loss, actuarial losses, tax	16	3
Reclassification out of Accumulated Other Comprehensive Income
Class of Stock [Line Items]
Net income	(65)	(43)
Reclassification out of Accumulated Other Comprehensive Income | Net Unrealized Gains (Losses) on Available-for-Sale Securities
Class of Stock [Line Items]
Gains (losses) from sales of available-for-sale securities, net	(42)	0
Reclassification out of Accumulated Other Comprehensive Income | Net Unrealized Gains (Losses) on Cash Flow Hedges
Class of Stock [Line Items]
Net interest income	(70)	(52)
Reclassification out of Accumulated Other Comprehensive Income | Amortization of Actuarial Losses
Class of Stock [Line Items]
Compensation and employee benefits expenses	$ 47	$ 9