Short-Term Debt - Mortgage Loans Sold Under Agreement to Repurchase by Counterparty (Details) - Loan Repo Facility $ in Thousands	Sep. 30, 2025 USD ($)
Atlas Securitized Products, L.P., Goldman Sachs Bank USA, Nomura Corporate Funding Americas and Mizuho Bank, Ltd
Mortgage loans sold under agreement to repurchase
Amount at risk	$ 6,908,399
Royal Bank of Canada
Mortgage loans sold under agreement to repurchase
Amount at risk	45,082
Bank of America, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	88,716
Atlas Securitized Products, L.P.
Mortgage loans sold under agreement to repurchase
Amount at risk	196,889
BNP Paribas
Mortgage loans sold under agreement to repurchase
Amount at risk	18,641
Barclays Capital
Mortgage loans sold under agreement to repurchase
Amount at risk	3,705
Nomura Corporate Funding Americas
Mortgage loans sold under agreement to repurchase
Amount at risk	27,613
Citibank, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	31,591
Wells Fargo Bank, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	20,975
Morgan Stanley Bank, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	24,814
Goldman Sachs
Mortgage loans sold under agreement to repurchase
Amount at risk	6,225
Mizuho Bank, Ltd.
Mortgage loans sold under agreement to repurchase
Amount at risk	33,596
JPMorgan Chase Bank, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	$ 28,159