Derivative Instruments and Hedging Activities (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	$ 22,342	$ 22,148
Deferred losses	173
Derivatives (included in other liabilities)	388	333
Cash collateral pledged for derivative liabilities	1
Additional collateral that would be required to be pledge if credit rating was downgraded by one notch	0
Derivatives designated as hedging instruments:
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	5,920	6,521
Parent
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives (included in other liabilities)	388
Other liabilities
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives (included in other liabilities)	388	333
Other liabilities | Derivatives designated as hedging instruments:
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives (included in other liabilities)	0	0
Fair Value Hedging | Interest rate swaps | Derivatives designated as hedging instruments:
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	0	0
Fair Value Hedging | Asset hedges: Pay-fixed interest rate swaps | Derivatives designated as hedging instruments:
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	4,570	4,571
Fair Value Hedging | Other liabilities | Interest rate swaps | Derivatives designated as hedging instruments:
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives (included in other liabilities)	0	0
Fair Value Hedging | Other liabilities | Asset hedges: Pay-fixed interest rate swaps | Derivatives designated as hedging instruments:
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives (included in other liabilities)	0	0
Cash Flow Hedging | Interest rate swaps | Derivatives designated as hedging instruments:
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	850	1,450
Cash Flow Hedging | Asset hedges: Pay-fixed interest rate swaps | Derivatives designated as hedging instruments:
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	1,000
Cash Flow Hedging | Pay-Fixed, receive-floating swap | Derivatives designated as hedging instruments:
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	3,600
Cash Flow Hedging | Other liabilities | Interest rate swaps | Derivatives designated as hedging instruments:
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives (included in other liabilities)	$ 0	$ 0