LEASES - Components of Net Investment in Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Net investment in the lease — lease payment receivable	$ 594,469	$ 589,120
Net investment in the lease — unguaranteed residual value in assets	45,429	44,704
Net investment in the lease, gross	639,898	633,824
Estimated loss allowance	(4,025)	(4,025)
Total	$ 635,873	$ 629,799