VARIABLE INTEREST ENTITIES - Schedule of the Fair Value of OBX Trusts Closed (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020	Jul. 31, 2020	Feb. 29, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Jun. 30, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Aug. 31, 2018	Mar. 31, 2018
OBX Trust | Consolidated VIEs
Variable Interest Entity [Line Items]
Loans	$ 257,135	$ 514,609	$ 489,352	$ 467,511	$ 374,609	$ 465,492	$ 463,405	$ 383,760	$ 388,156	$ 393,961	$ 384,027	$ 383,451	$ 327,162