Derivative Instruments and Hedging Activities (Long-term debt hedged items) (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022
Derivative Instruments, Gain (Loss) [Line Items]
Cumulative amount of fair value hedging adjustment included in the carrying amount of the hedged assets	$ 16,000,000
Total debt securities	11,759,000,000	$ 13,538,000,000
Derivative, Amount of Hedged Item	3,500,000,000
Fair Value Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Par value of hedged liabilities	0	(500,000,000)
Carrying amount of hedged liabilities	0	(435,000,000)
Cumulative amount of fair value hedging adjustment included in the carrying amount of the hedged liabilities	0	65,000,000
Par value of hedged assets	12,389,000,000	1,228,000,000
Carrying amount of hedged assets	12,209,000,000	962,000,000
Cumulative amount of fair value hedging adjustment included in the carrying amount of the hedged assets	(180,000,000)	$ (266,000,000)
Total debt securities	$ 11,300,000,000