Warehouse Facilities Collateralized by U.S. Government Sponsored Enterprises (Details) - USD ($)	1 Months Ended		3 Months Ended	12 Months Ended
	Mar. 30, 2020	Mar. 12, 2020	Mar. 31, 2020	Dec. 31, 2019	Mar. 13, 2020
Securities Financing Transaction [Line Items]
Warehouse facilities collateralized by U.S. Government Sponsored Enterprises			$ 703,321,000	$ 209,648,000
Uncommitted Lines
Securities Financing Transaction [Line Items]
Lines available			700,000,000
Committed Lines
Securities Financing Transaction [Line Items]
Lines available			1,050,000,000
Warehouse Facility Due June 17, 2020
Securities Financing Transaction [Line Items]
Warehouse facilities collateralized by U.S. Government Sponsored Enterprises			$ 182,159,000	$ 16,759,000
Basis spread on variable rate			1.15%	1.15%
Warehouse Facility Due June 17, 2020 | Uncommitted Lines
Securities Financing Transaction [Line Items]
Lines available			$ 300,000,000
Basis spread on variable rate			1.10%	1.10%
Warehouse Facility Due June 17, 2020 | Committed Lines
Securities Financing Transaction [Line Items]
Lines available			$ 450,000,000
Warehouse facilities collateralized by U.S. Government Sponsored Enterprises	$ 800,000,000.0
Warehouse credit facility increase (decrease)	$ 350,000,000.0
Warehouse Facility Due September 25, 2020
Securities Financing Transaction [Line Items]
Warehouse facilities collateralized by U.S. Government Sponsored Enterprises			$ 119,981,000	$ 8,097,000
Basis spread on variable rate			1.15%	1.15%
Warehouse Facility Due September 25, 2020 | Committed Lines
Securities Financing Transaction [Line Items]
Lines available			$ 200,000,000
Warehouse Facility Due October 9, 2020
Securities Financing Transaction [Line Items]
Warehouse facilities collateralized by U.S. Government Sponsored Enterprises			$ 389,260,000	$ 34,125,000
Basis spread on variable rate			1.15%	1.15%
Warehouse Facility Due October 9, 2020 | Committed Lines
Securities Financing Transaction [Line Items]
Lines available			$ 400,000,000
Warehouse facilities collateralized by U.S. Government Sponsored Enterprises					$ 500,000,000.0
Warehouse credit facility increase (decrease)		$ 100,000,000.0
Fannie Mae Repurchase Agreement, Open Maturity
Securities Financing Transaction [Line Items]
Warehouse facilities collateralized by U.S. Government Sponsored Enterprises			$ 11,921,000	$ 150,667,000
Basis spread on variable rate			1.05%	1.05%
Fannie Mae Repurchase Agreement, Open Maturity | Uncommitted Lines
Securities Financing Transaction [Line Items]
Lines available			$ 400,000,000