Short-Term Borrowings - Mortgage Loans Sold Under Agreement to Repurchase by Counterparty (Details) - Loan Repo Facility $ in Thousands	Dec. 31, 2022 USD ($)
Credit Suisse First Boston Mortgage Capital LLC Tranche Two
Mortgage loans sold under agreement to repurchase
Amount at risk	$ 3,831,311
Credit Suisse First Boston Mortgage Capital LLC Tranche One
Mortgage loans sold under agreement to repurchase
Amount at risk	75,634
Bank of America, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	68,918
JP Morgan Chase Bank
Mortgage loans sold under agreement to repurchase
Amount at risk	13,316
JP Morgan
Mortgage loans sold under agreement to repurchase
Amount at risk	11,908
BNP Paribas
Mortgage loans sold under agreement to repurchase
Amount at risk	11,131
Barclays
Mortgage loans sold under agreement to repurchase
Amount at risk	7,248
Goldman Sachs
Mortgage loans sold under agreement to repurchase
Amount at risk	4,326
Citibank, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	1,657
Morgan Stanley Bank, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	8,310
Royal Bank of Canada
Mortgage loans sold under agreement to repurchase
Amount at risk	19,895
Wells Fargo Bank, N.A.
Mortgage loans sold under agreement to repurchase
Amount at risk	$ 9,664