Derivative Financial Instruments - Offsetting of Derivative Assets - Offsetting of Derivative and Financial Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Derivatives: Subject to master netting arrangements:
Gross amounts of recognized liabilities	$ 204,570	$ 53,422
Netting	(155,551)	(32,096)
Net amounts of liabilities presented in the balance sheet	49,019	21,326
Total.
Gross amounts of recognized liabilities	246,388	54,702
Net amounts of liabilities presented in the consolidated balance sheet	90,837	22,606
Mortgage loans sold under agreements to repurchase
Net amounts of liabilities presented in the consolidated balance sheet	3,336,577
Debt Issuance Costs
Debt issuance costs, gross	(3,133)	(4,625)
Debt issuance costs	(3,133)	(4,625)
Gross amounts of recognized liabilities	3,333,444	7,292,735
Net amount of liabilities in the consolidated balance sheet	3,333,444	7,292,735
Total
Gross amounts of recognized liabilities	3,579,832	7,347,437
Gross amounts offset in the consolidated balance sheet	(155,551)	(32,096)
Net amounts of liabilities presented in the consolidated balance sheet	3,427,414	7,319,966
Net amount of liabilities in the consolidated balance sheet	90,837	22,606
Receivable from Counterparties
Total
Net amounts of liabilities presented in the consolidated balance sheet	3,424,281	7,315,341
Loan Repo Facility
Mortgage loans sold under agreements to repurchase
Gross amounts of recognized liabilities	3,336,577	7,297,360
Net amounts of liabilities presented in the consolidated balance sheet	3,336,577	7,297,360
Net amounts of liabilities presented in the consolidated balance sheet	3,336,577	7,297,360
Debt Issuance Costs
Debt issuance costs	(3,133)	(4,625)
Net amount of liabilities in the consolidated balance sheet	3,333,444	7,292,735
Forward contracts | Purchases
Derivatives: Subject to master netting arrangements:
Gross amounts of recognized liabilities	162,584	18,007
Net amounts of liabilities presented in the balance sheet	162,584	18,007
Total.
Gross amounts of recognized liabilities	162,584	18,007
Forward contracts | Sales
Derivatives: Subject to master netting arrangements:
Gross amounts of recognized liabilities	35,283	35,415
Net amounts of liabilities presented in the balance sheet	35,283	35,415
Total.
Gross amounts of recognized liabilities	35,283	35,415
Interest rate lock commitments
Derivatives not subject to master netting arrangements
Gross amounts of recognized liabilities	41,818	1,280
Total
Net amounts of liabilities presented in the consolidated balance sheet	41,818	1,280
Net amount of liabilities in the consolidated balance sheet	41,818	$ 1,280
Put options on Eurodollar futures | Sales
Derivatives: Subject to master netting arrangements:
Gross amounts of recognized liabilities	6,703
Net amounts of liabilities presented in the balance sheet	6,703
Total.
Gross amounts of recognized liabilities	$ 6,703