Long-Term Debt (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2023	Jun. 30, 2023
Debt Instrument [Line Items]
Subordinated notes, Par amount		$ 588
SOFR
Debt Instrument [Line Items]
Annual floating rate basis spread on variable rate		4.15%
Senior Notes, Interest Rate 3.50% | Senior Notes
Debt Instrument [Line Items]
Redemption of senior debt	$ 128
Subordinated Notes, Interest Rate 3.25%
Debt Instrument [Line Items]
Subordinated notes, Par amount		$ 500
Subordinated Notes, Interest Rate 3.25% | Subordinated Debt
Debt Instrument [Line Items]
Debt interest rate		3.25%
Subordinated Notes, Interest Rate 6.95%
Debt Instrument [Line Items]
Subordinated notes, Par amount		$ 88
Subordinated Notes, Interest Rate 6.95% | Subordinated Debt
Debt Instrument [Line Items]
Debt interest rate		6.95%
Senior Note, Interest Rate 4.50 | Senior Notes
Debt Instrument [Line Items]
Debt interest rate			4.50%