Short-Term Debt - Mortgage Loans Sold Under Agreement to Repurchase by Counterparty (Details) - Loan Repo Facility $ in Thousands	Sep. 30, 2022 USD ($)
Credit Suisse First Boston Mortgage Capital LLC Tranche Two
Mortgage loans sold under agreement to repurchase
Amount at risk	$ 3,451,397
Credit Suisse First Boston Mortgage Capital LLC Tranche One
Mortgage loans sold under agreement to repurchase
Amount at risk	39,317
Bank of America, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	5,367
JP Morgan Chase Bank
Mortgage loans sold under agreement to repurchase
Amount at risk	39,006
JP Morgan
Mortgage loans sold under agreement to repurchase
Amount at risk	77,947
BNP Paribas
Mortgage loans sold under agreement to repurchase
Amount at risk	13,192
Barclays
Mortgage loans sold under agreement to repurchase
Amount at risk	11,178
Goldman Sachs
Mortgage loans sold under agreement to repurchase
Amount at risk	414
Citibank, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	7,062
Morgan Stanley Bank, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	23,564
Royal Bank of Canada
Mortgage loans sold under agreement to repurchase
Amount at risk	$ 24,518