Subsequent Events Subsequent Events (Details) - USD ($) $ in Millions					6 Months Ended
		Jul. 26, 2019	Jul. 25, 2019	Jul. 12, 2019	Jun. 30, 2019		Dec. 31, 2018
Warehouse Facility II [Member]
Debt Instrument [Line Items]
Debt facility financing amount	[1],[2]				$ 400.0
Debt maturity date	[1],[3]				Dec. 20, 2020
Warehouse Facility VI [Member]
Debt Instrument [Line Items]
Debt facility financing amount	[1],[2]				$ 75.0
Debt maturity date	[1],[3]				Sep. 30, 2020
Warehouse Facility IV [Member]
Debt Instrument [Line Items]
Debt facility financing amount					$ 250.0	[1],[2]	$ 250.0
Debt maturity date	[1],[3]				Apr. 30, 2020
Subsequent Event [Member] | Warehouse Facility II [Member]
Debt Instrument [Line Items]
Debt maturity date	[1],[3]			Jul. 12, 2022
Subsequent Event [Member] | Warehouse Facility VI [Member]
Debt Instrument [Line Items]
Debt maturity date	[1],[3]		Sep. 30, 2022
Subsequent Event [Member] | Warehouse Facility IV [Member]
Debt Instrument [Line Items]
Debt facility financing amount	[1],[2]	$ 300.0
Debt maturity date	[1],[3]	Jul. 26, 2022
Subsequent Event [Member] | Warehouse Facility VIII [Member]
Debt Instrument [Line Items]
Debt facility financing amount	[1],[2]	$ 200.0
Debt maturity date	[1],[3]	Jul. 26, 2022
LIBOR [Member] | Warehouse Facility II [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	[1],[2]				17500.00%
LIBOR [Member] | Warehouse Facility VI [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	[1]				20000.00%
LIBOR [Member] | Warehouse Facility IV [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	[1],[2]				22500.00%
LIBOR [Member] | Subsequent Event [Member] | Warehouse Facility IV [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	[1],[2]	20000.00%
LIBOR [Member] | Subsequent Event [Member] | Warehouse Facility VIII [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	[1],[2]	19000.00%

[1] Financing made available only to a specified subsidiary of the Company.

[2] Interest rate cap agreements are in place to limit the exposure to increasing interest rates

[3] Represents the revolving maturity date. The outstanding balance will amortize after the revolving maturity date based on the cash flows of the pledged assets.