Loans Held for Sale, at Fair Value - Summary of Loans Held for Sale at Cost Basis and Fair Value (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable
Fair Value	$ 1,089,429	$ 215,290
Cost Basis
Accounts, Notes, Loans and Financing Receivable
Fair Value	1,064,271	210,116
Fair Value
Accounts, Notes, Loans and Financing Receivable
Fair Value	$ 1,089,429	$ 215,290