Short-Term Debt - Mortgage Loans Sold Under Agreement to Repurchase by Counterparty (Details) - Loan Repo Facility $ in Thousands	Mar. 31, 2023 USD ($)
Credit Suisse First Boston Mortgage Capital LLC Tranche Two
Mortgage loans sold under agreement to repurchase
Amount at risk	$ 3,068,850
Bank of America, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	166,185
JP Morgan Chase Bank
Mortgage loans sold under agreement to repurchase
Amount at risk	10,667
JP Morgan
Mortgage loans sold under agreement to repurchase
Amount at risk	83,772
BNP Paribas
Mortgage loans sold under agreement to repurchase
Amount at risk	19,801
Atlas Securitized Products, L.P.
Mortgage loans sold under agreement to repurchase
Amount at risk	75,661
Barclays
Mortgage loans sold under agreement to repurchase
Amount at risk	38,521
Goldman Sachs
Mortgage loans sold under agreement to repurchase
Amount at risk	8,935
Citibank, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	30,114
Morgan Stanley Bank, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	31,024
Royal Bank of Canada
Mortgage loans sold under agreement to repurchase
Amount at risk	23,068
Wells Fargo Bank, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	$ 19,112