Shareholders' Equity - Adjustments to Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Class of Stock [Line Items]
Net interest income	$ (509)	$ (467)
Compensation and employee benefits expenses	1,232	1,242
Net income	(604)	(519)
Other comprehensive income (loss), cash flow hedge, gain (loss), reclassification, tax	6	6
Other comprehensive (income) loss, actuarial losses, tax	6	3
Reclassification out of Accumulated Other Comprehensive Income
Class of Stock [Line Items]
Net income	(1)	(7)
Reclassification out of Accumulated Other Comprehensive Income | Net Unrealized Gains (Losses) on Cash Flow Hedges
Class of Stock [Line Items]
Net interest income	(16)	(15)
Reclassification out of Accumulated Other Comprehensive Income | Amortization of Actuarial Losses
Class of Stock [Line Items]
Compensation and employee benefits expenses	$ 15	$ 8