Derivative Instruments and Hedging Activities (Notional and Recorded Fair Values) (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Notional amount	$ 22,610,000,000	$ 17,877,000,000
Derivative asset, fair value	219,000,000	418,000,000
Derivative liability, fair value	51,000,000	38,000,000
Net credit valuation adjustment reducing fair value	3,000,000	18,000,000
Other assets
Derivative [Line Items]
Derivative asset, fair value	249,000,000	420,000,000
Other liabilities
Derivative [Line Items]
Derivative liability, fair value	236,000,000	418,000,000
Derivatives designated as hedging instruments
Derivative [Line Items]
Notional amount	7,862,000,000	4,033,000,000
Derivatives designated as hedging instruments | Other assets
Derivative [Line Items]
Derivative asset, fair value	10,000,000	3,000,000
Derivatives designated as hedging instruments | Other liabilities
Derivative [Line Items]
Derivative liability, fair value	0	0
Derivatives designated as hedging instruments | Purchased interest rate floors | Cash Flow Hedging
Derivative [Line Items]
Notional amount	0	0
Derivatives designated as hedging instruments | Purchased interest rate floors | Other assets | Cash Flow Hedging
Derivative [Line Items]
Derivative asset, fair value	0	0
Derivatives designated as hedging instruments | Purchased interest rate floors | Other liabilities | Cash Flow Hedging
Derivative [Line Items]
Derivative liability, fair value	0	0
Derivatives designated as hedging instruments | Interest rate swaps | Cash Flow Hedging
Derivative [Line Items]
Notional amount	6,883,000,000	3,150,000,000
Derivatives designated as hedging instruments | Interest rate swaps | Fair Value Hedging
Derivative [Line Items]
Notional amount	500,000,000	500,000,000
Derivatives designated as hedging instruments | Interest rate swaps | Other assets | Cash Flow Hedging
Derivative [Line Items]
Derivative asset, fair value	0	0
Derivatives designated as hedging instruments | Interest rate swaps | Other assets | Fair Value Hedging
Derivative [Line Items]
Derivative asset, fair value	0	0
Derivatives designated as hedging instruments | Interest rate swaps | Other liabilities | Cash Flow Hedging
Derivative [Line Items]
Derivative liability, fair value	0	0
Derivatives designated as hedging instruments | Interest rate swaps | Other liabilities | Fair Value Hedging
Derivative [Line Items]
Derivative liability, fair value	0	0
Derivatives designated as hedging instruments | Asset hedges: Pay-fixed interest rate swaps | Fair Value Hedging
Derivative [Line Items]
Notional amount	479,000,000	383,000,000
Derivatives designated as hedging instruments | Asset hedges: Pay-fixed interest rate swaps | Other assets | Fair Value Hedging
Derivative [Line Items]
Derivative asset, fair value	10,000,000	3,000,000
Derivatives designated as hedging instruments | Asset hedges: Pay-fixed interest rate swaps | Other liabilities | Fair Value Hedging
Derivative [Line Items]
Derivative liability, fair value	0	0
Derivatives not designated as hedging instruments
Derivative [Line Items]
Notional amount	14,748,000,000	13,844,000,000
Derivatives not designated as hedging instruments | Other assets
Derivative [Line Items]
Derivative asset, fair value	239,000,000	417,000,000
Derivatives not designated as hedging instruments | Other liabilities
Derivative [Line Items]
Derivative liability, fair value	236,000,000	418,000,000
Derivatives not designated as hedging instruments | Customer-facing interest rate derivatives
Derivative [Line Items]
Notional amount	6,587,000,000	5,986,000,000
Derivatives not designated as hedging instruments | Customer-facing interest rate derivatives | Other assets
Derivative [Line Items]
Derivative asset, fair value	192,000,000	390,000,000
Derivatives not designated as hedging instruments | Customer-facing interest rate derivatives | Other liabilities
Derivative [Line Items]
Derivative liability, fair value	36,000,000	2,000,000
Derivatives not designated as hedging instruments | Offsetting interest rate derivatives
Derivative [Line Items]
Notional amount	6,587,000,000	5,986,000,000
Derivatives not designated as hedging instruments | Offsetting interest rate derivatives | Other assets
Derivative [Line Items]
Derivative asset, fair value	38,000,000	3,000,000
Derivatives not designated as hedging instruments | Offsetting interest rate derivatives | Other assets | Fair Value Hedging
Derivative [Line Items]
Derivative asset, fair value	8,000,000	1,000,000
Derivatives not designated as hedging instruments | Offsetting interest rate derivatives | Other liabilities
Derivative [Line Items]
Derivative liability, fair value	197,000,000	409,000,000
Derivatives not designated as hedging instruments | Offsetting interest rate derivatives | Other liabilities | Fair Value Hedging
Derivative [Line Items]
Derivative liability, fair value	12,000,000	29,000,000
Derivatives not designated as hedging instruments | Other interest rate derivatives
Derivative [Line Items]
Notional amount	1,286,000,000	1,649,000,000
Derivatives not designated as hedging instruments | Other interest rate derivatives | Other assets
Derivative [Line Items]
Derivative asset, fair value	6,000,000	20,000,000
Derivatives not designated as hedging instruments | Other interest rate derivatives | Other liabilities
Derivative [Line Items]
Derivative liability, fair value	1,000,000	3,000,000
Derivatives not designated as hedging instruments | Foreign exchange derivatives
Derivative [Line Items]
Notional amount	288,000,000	223,000,000
Derivatives not designated as hedging instruments | Foreign exchange derivatives | Other assets
Derivative [Line Items]
Derivative asset, fair value	3,000,000	4,000,000
Derivatives not designated as hedging instruments | Foreign exchange derivatives | Other liabilities
Derivative [Line Items]
Derivative liability, fair value	$ 2,000,000	$ 4,000,000