SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Provision for Credit Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Components of Provision for Credit Losses
Provision (benefit) for loan losses	$ (610)	$ 3,739	$ 875
Provision (benefit) for risk-sharing obligations	(12,677)	33,740	6,398
Provision (benefit) for credit losses	$ (13,287)	$ 37,479	$ 7,273