Derivatives - Schedule of Interest Rate Hedging Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Derivative [Line Items]
Margin deposit assets	$ 328,000	$ 219,000
Interest rate swaps | Short position | Not Designated as Hedging Instrument, Economic Hedge
Derivative [Line Items]
Notional balance	$ (7,860,000)	$ (5,385,000)
Derivative, average fixed interest rate	3.70%	3.61%
Interest rate swaps | Short position | Not Designated as Hedging Instrument, Economic Hedge | 4-5 years
Derivative [Line Items]
Notional balance	$ (1,550,000)	$ (1,275,000)
Derivative, average fixed interest rate	3.42%	3.42%
Interest rate swaps | Short position | Not Designated as Hedging Instrument, Economic Hedge | 6-7 years
Derivative [Line Items]
Notional balance	$ (3,760,000)	$ (3,085,000)
Derivative, average fixed interest rate	3.67%	3.61%
Interest rate swaps | Short position | Not Designated as Hedging Instrument, Economic Hedge | 9-10 years
Derivative [Line Items]
Notional balance	$ (2,550,000)	$ (1,025,000)
Derivative, average fixed interest rate	3.90%	3.83%
U.S. Treasury futures | Short position | 5-6 years | Not Designated as Hedging Instrument, Economic Hedge
Derivative [Line Items]
Notional balance	$ (30,000)	$ 0
U.S. Treasury futures | Short position | 10-year | Not Designated as Hedging Instrument, Economic Hedge
Derivative [Line Items]
Notional balance	(1,190,000)	(735,000)
U.S. Treasury futures | Short position | 30-year | Not Designated as Hedging Instrument, Economic Hedge
Derivative [Line Items]
Notional balance	(953,500)	(516,500)
U.S. Treasury futures | Short position | Not Designated as Hedging Instrument, Economic Hedge
Derivative [Line Items]
Notional balance	$ (2,173,500)	$ (1,251,500)