Warehouse Borrowings - Additional Information (Details) - Warehouse Agreement Borrowings - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Aug. 04, 2017
Short-term Debt [Line Items]
Aggregate funding capacity	$ 2,400.0
Variable interest rate basis	LIBOR
Expiration dates through	May 21, 2018
Minimum
Short-term Debt [Line Items]
Basis spread on variable interest rate	2.10%
Maximum
Short-term Debt [Line Items]
Basis spread on variable interest rate	3.13%
One Credit Facility Used to Repurchase HECMs | Subsequent Event
Short-term Debt [Line Items]
Increase in aggregate capacity		$ 100.0
Borrowings to fund purchase or origination of residential loans
Short-term Debt [Line Items]
Days to Transfer Loans	20 days
Borrowings to fund purchase or origination of residential loans | Minimum
Short-term Debt [Line Items]
Repayment Terms	60 days
Borrowings to fund purchase or origination of residential loans | Maximum
Short-term Debt [Line Items]
Repayment Terms	90 days
Borrowings to fund repurchase of HECMs | Minimum
Short-term Debt [Line Items]
Repayment Terms	120 days
Borrowings to fund repurchase of HECMs | Maximum
Short-term Debt [Line Items]
Repayment Terms	364 days
Borrowings to fund repurchase of real estate owned | Minimum
Short-term Debt [Line Items]
Repayment Terms	180 days
Borrowings to fund repurchase of real estate owned | Maximum
Short-term Debt [Line Items]
Repayment Terms	364 days
Residential Mortgage
Short-term Debt [Line Items]
Outstanding borrowings, secured	$ 900.0
Pledged as collateral	1,000.0
Repurchased HECMs And Real Estate Owned
Short-term Debt [Line Items]
Outstanding borrowings, secured	440.9
Pledged as collateral	$ 522.5