Borrowings and Financing Activities - Schedule of Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Total secured borrowings	$ 207,601	$ 119,476
Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Debt Instrument [Line Items]
FHLB, floating SOFR advances	$ 13,000	$ 13,000
FHLB, weighted average interest rate	5.532%	5.602%
Senior notes
Debt Instrument [Line Items]
Long-term debt	$ 1,512,860	$ 1,417,781
Senior notes | Senior Notes due 2024
Debt Instrument [Line Items]
Interest rate on senior notes	4.50%
Long-term debt	$ 449,354	449,037
Senior notes | Senior Notes due 2025
Debt Instrument [Line Items]
Interest rate on senior notes	6.625%
Long-term debt	$ 0	522,343
Senior notes | Senior Notes due 2027
Debt Instrument [Line Items]
Interest rate on senior notes	4.875%
Long-term debt	$ 446,661	446,401
Senior notes | Senior Notes due 2029
Debt Instrument [Line Items]
Interest rate on senior notes	6.20%
Long-term debt	$ 616,845	0
FHLB advances
Debt Instrument [Line Items]
FHLB advances due 2024, average interest rate	4.73%
FHLB advances due 2025, average interest rate	2.34%
FHLB advances due 2026, average interest rate	4.469%
FHLB advances due 2027, average interest rate	2.562%
2024	$ 56,875	72,871
2025	12,684	12,684
2026	1,835	1,835
2027	7,887	7,887
Total FHLB advances	79,281	95,277
Mortgage loan financing facilities
Debt Instrument [Line Items]
Long-term debt	$ 128,320	$ 24,199
Mortgage financing facilities, average interest rate	7.097%