Goodwill and Intangible Assets, Net - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended				11 Months Ended	12 Months Ended
	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Feb. 09, 2018	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill impairment charges				$ 0	$ 8,960	$ 0
Amortization expense for intangible assets				$ 200	$ 14,200	$ 3,200
Servicing [Member]
Goodwill [Line Items]
Intangible assets impairment charge	$ 6,400		$ 1,000
Originations [Member]
Goodwill [Line Items]
Goodwill impairment charges			$ 9,000
Intangible assets impairment charge	$ 6,300	$ 1,000