Financing Agreements - Junior Subordinated Notes (Details) - 4.7% Fixed-to-Floating Rate Junior Subordinated Notes, due 2048 - Junior Subordinated Notes - USD ($) $ in Millions	Jan. 23, 2018	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Annual interest rate on loan	4.70%	4.70%	4.70%
Basis spread	2.084%
Amount of unsecured notes issued	$ 340	$ 10