Short-Term and Long-Term Debt (Schedule of Junior Subordinated Notes) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Junior Subordinated Retail Notes March 2013
Debt Instrument [Line Items]
Principal Amount	$ 500
Interest Rate	5.20%
Interest Rate Subsequent to Optional Redemption Date	SOFR + 3.30% (2)
Junior Subordinated Retail Notes May 2015
Debt Instrument [Line Items]
Principal Amount	$ 1,000
Interest Rate	5.38%
Interest Rate Subsequent to Optional Redemption Date	SOFR + 3.29% (2)
Junior Subordinated Institutional Notes September 2017
Debt Instrument [Line Items]
Principal Amount	$ 750
Interest Rate	4.50%
Interest Rate Subsequent to Optional Redemption Date	SOFR + 2.64% (2)
Junior Subordinated Institutional Notes August 2018
Debt Instrument [Line Items]
Principal Amount	$ 565
Interest Rate	5.63%
Junior Subordinated Institutional Notes September 2018
Debt Instrument [Line Items]
Principal Amount	$ 1,000
Interest Rate	5.70%
Interest Rate Subsequent to Optional Redemption Date	SOFR + 2.93% (2)
Junior Subordinated Retail Notes August 2020 4.13%
Debt Instrument [Line Items]
Principal Amount	$ 500
Interest Rate	4.13%
Junior Subordinated Institutional Notes August 2020 3.70% [Member]
Debt Instrument [Line Items]
Principal Amount	$ 800
Interest Rate	3.70%
Interest Rate Subsequent to Optional Redemption Date	US Treasury + 3.04
Junior Subordinated Institutional Notes February 2022
Debt Instrument [Line Items]
Principal Amount	$ 1,000
Interest Rate	5.13%
Interest Rate Subsequent to Optional Redemption Date	US Treasury + 3.16
Junior Subordinated Institutional Notes August 2022 6.00%
Debt Instrument [Line Items]
Principal Amount	$ 1,200
Interest Rate	6.00%
Interest Rate Subsequent to Optional Redemption Date	US Treasury + 3.23
Junior Subordinated Institutional Notes August 2022 5.95%
Debt Instrument [Line Items]
Principal Amount	$ 300
Interest Rate	5.95%
Junior Subordinated Institutional Notes February 2023
Debt Instrument [Line Items]
Principal Amount	$ 500
Interest Rate	6.75%
Interest Rate Subsequent to Optional Redemption Date	US Treasury + 2.85