Servicing Advance Liabilities - Schedule of Servicing Advance Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Summary of Servicing Advance Liabilities Table [Line Items]
Servicing advance liabilities	$ 218,291	$ 483,462
Servicing Advance Facilities [Member]
Summary of Servicing Advance Liabilities Table [Line Items]
Servicing advance liabilities	218,291	421,165
Early Advance Reimbursement Agreement [Member]
Summary of Servicing Advance Liabilities Table [Line Items]
Servicing advance liabilities	$ 0	$ 62,297