Derivative Instruments and Hedging Activities (Narrative) (Details)	3 Months Ended
	Mar. 31, 2022 USD ($) derivative_instrument	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	$ 22,186,000,000		$ 22,610,000,000
Amortization of cumulative debt basis adjustments	1,000,000
Redesignated swaps, unamortized basis adjustments	7,000,000
Decrease in cash flow hedge portfolio	192,000,000
Other liabilities	179,000,000		51,000,000
Cash collateral pledged for derivative liabilities	118,000,000
Additional collateral that would be required to be pledge if credit rating was downgraded by one notch	1,000,000
Parent [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Other liabilities	179,000,000
Other liabilities
Derivative Instruments, Gain (Loss) [Line Items]
Other liabilities	217,000,000		236,000,000
Derivatives designated as hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	7,531,000,000		7,862,000,000
Decrease in cash flow hedge portfolio	178,000,000	$ 5,000,000
Derivatives designated as hedges | Other liabilities
Derivative Instruments, Gain (Loss) [Line Items]
Other liabilities	$ 0		0
Fair Value Hedging | Derivatives designated as hedges | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Number of interest rate derivatives remaining | derivative_instrument	1
Derivative, notional amount	$ 500,000,000		500,000,000
Increase (decrease) in fair value hedges	7,000,000
Fair Value Hedging | Derivatives designated as hedges | Asset hedges: Pay-fixed interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	990,000,000		479,000,000
Increase (decrease) in fair value hedges	(52,000,000)
Decrease in cash flow hedge portfolio	0	0
Fair Value Hedging | Derivatives designated as hedges | Other liabilities | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Other liabilities	0		0
Fair Value Hedging | Derivatives designated as hedges | Other liabilities | Asset hedges: Pay-fixed interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Other liabilities	0		0
Cash Flow Hedging | Derivatives designated as hedges | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	6,041,000,000		6,883,000,000
Decrease in cash flow hedge portfolio	178,000,000	$ 5,000,000
Cash Flow Hedging | Derivatives designated as hedges | Other liabilities | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Other liabilities	$ 0		$ 0