Derivative Financial Instruments - Total Notional or Contractual Amounts, Fair Value, Collateral and Net Exposure of Derivative Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Derivative [Line Items]
Derivative Assets	$ 230	$ 288
Derivative Liabilities	284	238
Derivative Assets, Total	560	565
Derivative Liabilities, Total	284	238
Reduction in derivative liabilities due to rules of clearing houses	313	112
Interest rate swaps
Derivative [Line Items]
Derivative Assets		18
Foreign exchange forwards and swaps
Derivative [Line Items]
Derivative Assets	169	162
Derivative Liabilities	157	128
Total return swaps
Derivative [Line Items]
Derivative Liabilities	8
Client foreign currency options
Derivative [Line Items]
Derivative Assets	10	9
Derivative Liabilities	10	9
Client interest rate derivatives
Derivative [Line Items]
Derivative Assets	51	99
Derivative Liabilities	109	101
Derivatives designated as hedging instruments | Interest rate swaps | Other assets
Derivative [Line Items]
Derivative Asset, Notional or Contractual Amount	5,900	10,700
Derivative Assets	0	18
Derivatives designated as hedging instruments | Interest rate swaps | Other liabilities
Derivative [Line Items]
Derivative Liabilities, Notional or Contractual Amount	0	0
Derivative Liabilities	0	0
Derivatives not designated as hedging instruments
Derivative [Line Items]
Derivative Assets	560	547
Derivative Liabilities	284	238
Derivatives not designated as hedging instruments | Foreign exchange forwards and swaps | Other assets
Derivative [Line Items]
Derivative Asset, Notional or Contractual Amount	586	701
Derivative Assets	1	16
Derivatives not designated as hedging instruments | Foreign exchange forwards and swaps | Other liabilities
Derivative [Line Items]
Derivative Liabilities, Notional or Contractual Amount	852	62
Derivative Liabilities	6	2
Derivatives not designated as hedging instruments | Equity warrant assets | Other assets
Derivative [Line Items]
Derivative Asset, Notional or Contractual Amount	334	322
Derivative Assets	323	277
Derivatives not designated as hedging instruments | Contingent conversion rights | Other assets
Derivative [Line Items]
Derivative Asset, Notional or Contractual Amount	50
Derivative Assets	7
Derivatives not designated as hedging instruments | Client foreign exchange forwards and swaps | Other assets
Derivative [Line Items]
Derivative Asset, Notional or Contractual Amount	8,522	8,245
Derivative Assets	168	146
Derivatives not designated as hedging instruments | Client foreign exchange forwards and swaps | Other liabilities
Derivative [Line Items]
Derivative Liabilities, Notional or Contractual Amount	7,915	7,764
Derivative Liabilities	151	126
Derivatives not designated as hedging instruments | Total return swaps | Other liabilities
Derivative [Line Items]
Derivative Liabilities, Notional or Contractual Amount	46
Derivative Liabilities	8
Derivatives not designated as hedging instruments | Client foreign currency options | Other assets
Derivative [Line Items]
Derivative Asset, Notional or Contractual Amount	556	688
Derivative Assets	10	9
Derivatives not designated as hedging instruments | Client foreign currency options | Other liabilities
Derivative [Line Items]
Derivative Liabilities, Notional or Contractual Amount	556	688
Derivative Liabilities	10	9
Derivatives not designated as hedging instruments | Client interest rate derivatives | Other assets
Derivative [Line Items]
Derivative Asset, Notional or Contractual Amount	2,117	2,178
Derivative Assets	51	99
Derivatives not designated as hedging instruments | Client interest rate derivatives | Other liabilities
Derivative [Line Items]
Derivative Liabilities, Notional or Contractual Amount	2,273	2,315
Derivative Liabilities	$ 109	$ 101