Loans Held for Sale, at Fair Value - Fair Value Adjustments on Loans Held for Sale (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts and Financing Receivables, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance [Abstract]
Interest income on loans held for sale	$ 27,560	$ 34,239	$ 31,607
Gains (loss) recognized on change in fair value on loans held for sale	$ 24,294	$ 5,174	$ 18,430