Derivative Financial Instruments - Offsetting of Derivative Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Derivatives not subject to master netting arrangements
Gross amounts of recognized assets	$ 325,808	$ 146,698
Derivatives subject to master netting arrangements:
Gross amounts of recognized assets	524,074	40,699
Gross amounts offset in the consolidated balance sheet	(416,671)	(27,711)
Net amounts of assets presented in the consolidated balance sheet	107,403	12,988
Total
Gross amounts of recognized assets	849,882	187,397
Net amounts of assets presented in the balance sheet	433,211	159,686
Interest rate lock commitments
Derivatives not subject to master netting arrangements
Gross amounts of recognized assets	317,621	138,511
Total
Net amounts of assets presented in the balance sheet	317,621	138,511
Repurchase agreement derivatives
Derivatives not subject to master netting arrangements
Gross amounts of recognized assets	8,187	8,187
MBS put options
Derivatives subject to master netting arrangements:
Gross amounts of recognized assets	4,062	3,415
Net amounts of assets presented in the consolidated balance sheet	4,062	3,415
Total
Gross amounts of recognized assets	4,062	3,415
Swaptions
Derivatives subject to master netting arrangements:
Gross amounts of recognized assets	36,696	2,409
Net amounts of assets presented in the consolidated balance sheet	36,696	2,409
Swaptions | Purchases
Total
Gross amounts of recognized assets	36,696	2,409
Forward contracts | Purchases
Derivatives subject to master netting arrangements:
Gross amounts of recognized assets	421,860	12,364
Net amounts of assets presented in the consolidated balance sheet	421,860	12,364
Total
Gross amounts of recognized assets	421,860	12,364
Forward contracts | Sales
Derivatives subject to master netting arrangements:
Gross amounts of recognized assets	23,346	17,097
Net amounts of assets presented in the consolidated balance sheet	23,346	17,097
Total
Gross amounts of recognized assets	23,346	17,097
Put options on interest rate futures | Purchases
Derivatives subject to master netting arrangements:
Gross amounts of recognized assets	13,676	3,945
Net amounts of assets presented in the consolidated balance sheet	13,676	3,945
Total
Gross amounts of recognized assets	13,676	3,945
Call options on interest rate futures | Purchases
Derivatives subject to master netting arrangements:
Gross amounts of recognized assets	24,434	1,469
Net amounts of assets presented in the consolidated balance sheet	24,434	1,469
Total
Gross amounts of recognized assets	$ 24,434	$ 1,469