Derivative Activities - Offsetting of Derivative Assets - Offsetting of Derivative and Financial Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Derivatives: Subject to master netting arrangements:
Gross amounts of recognized liabilities	$ 53,422	$ 252,425
Netting	(32,096)	(212,722)
Net amounts of liabilities presented in the balance sheet	21,326	39,703
Total.
Gross amounts of recognized liabilities	54,702	255,360
Net amounts of liabilities presented in the consolidated balance sheet	22,606	42,638
Mortgage loans sold under agreements to repurchase
Net amounts of liabilities presented in the consolidated balance sheet	7,297,360
Debt Issuance Costs
Debt issuance costs, gross	(4,625)	(9,198)
Debt issuance costs	(4,625)	(9,198)
Net amount of liabilities in the consolidated balance sheet	7,292,735	9,654,797
Total
Gross amounts of recognized liabilities	7,347,437	9,910,157
Gross amounts offset in the consolidated balance sheet	(32,096)	(212,722)
Net amounts of liabilities presented in the consolidated balance sheet	7,319,966	9,706,633
Net amount of liabilities in the consolidated balance sheet	22,606	42,638
Receivable from Counterparties
Total
Net amounts of liabilities presented in the consolidated balance sheet	7,315,341	9,697,435
Loan Repo Facility
Mortgage loans sold under agreements to repurchase
Gross amounts of recognized liabilities	7,297,360	9,663,995
Net amounts of liabilities presented in the consolidated balance sheet	7,297,360	9,663,995
Net amounts of liabilities presented in the consolidated balance sheet	7,297,360	9,663,995
Debt Issuance Costs
Debt issuance costs, gross	(4,625)	(9,198)
Gross amounts of recognized liabilities	7,292,735	9,654,797
Net amount of liabilities in the consolidated balance sheet	7,292,735	9,654,797
Forward contracts | Purchases
Derivatives: Subject to master netting arrangements:
Gross amounts of recognized liabilities	18,007	1,276
Net amounts of liabilities presented in the balance sheet	18,007	1,276
Forward contracts | Sales
Derivatives: Subject to master netting arrangements:
Gross amounts of recognized liabilities	35,415	251,149
Net amounts of liabilities presented in the balance sheet	35,415	251,149
Interest rate lock commitments
Derivatives not subject to master netting arrangements
Gross amounts of recognized liabilities	1,280	2,935
Total
Net amounts of liabilities presented in the consolidated balance sheet	1,280	2,935
Net amount of liabilities in the consolidated balance sheet	$ 1,280	$ 2,935