Derivatives - Derivative Information about U.S. Treasury Futures (Details) - USD ($)	Jun. 30, 2025	Dec. 31, 2024
Derivative [Line Items]
Derivative assets	$ 31,816,000	$ 133,000
Margin deposit assets	315,000,000	219,000,000
Variation margin payable, derivative	38,000,000
Variation margin receivable, derivative		10,000,000
U.S. Treasury futures
Derivative [Line Items]
Derivative assets	0
Derivative liabilities	69,000,000
Fair Value		1,000,000
Interest rate swaps
Derivative [Line Items]
Derivative assets	0
Fair Value	36,000,000	153,000,000
Interest Rate Swaption | Long position
Derivative [Line Items]
Derivative assets	993,000	$ 0
Fair Value	8,968,000
Margin deposit assets	$ 2,000,000