Derivative Financial Instruments - Carrying Amount and Cumulative Basis Adjustments for Hedge Accounting (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Prepayable financial asset closed portfolio, amortized cost	$ 667	$ 685
Prepayable financial asset closed portfolio, last-of-layer, amortized cost	400	400
Cumulative adjustment associated with hedging relationships	(11)	(6)
Hedged Items Currently Designated | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Hedged Assets/Liabilities	12,465	12,463
Cumulative Hedge Accounting Basis Adjustments	(400)	(340)
Hedged Items Currently Designated | Available-for-sale securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Hedged Assets/Liabilities	12,621	11,260
Cumulative Hedge Accounting Basis Adjustments	(605)	(503)
De-designated | Long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cumulative Hedge Accounting Basis Adjustments	142	156
De-designated | Available-for-sale securities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Cumulative Hedge Accounting Basis Adjustments	$ 2	$ 3