Capital Structure - Schedule of Interest Rates for LIBOR-Linked Debt (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Debt outstanding	$ 7,942	$ 7,964
Subordinated Debentures | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis spread on interest at floating rate	0.26161%
5.100% Subordinated Debentures, due 2053
Debt Instrument [Line Items]
Interest rate	5.10%
Debt outstanding	$ 500
5.100% Subordinated Debentures, due 2053 | Maximum | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis spread on interest at floating rate	3.165%
5.100% Subordinated Debentures, due 2053 | Minimum | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis spread on interest at floating rate	0.26161%
5.750% Subordinated Debentures, due 2053
Debt Instrument [Line Items]
Interest rate	5.75%
Debt outstanding	$ 800
5.750% Subordinated Debentures, due 2053 | Maximum | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis spread on interest at floating rate	2.938%
5.750% Subordinated Debentures, due 2053 | Minimum | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Basis spread on interest at floating rate	0.26161%