VARIABLE INTEREST ENTITIES - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Sep. 30, 2019	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Variable Interest Entity [Line Items]
Total assets	$ 7,770,138			$ 7,770,138		$ 7,828,410
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Funding transferred	0		$ 235	3,631	$ 235
Total assets	254,670			254,670		259,445
Maximum loss exposure	26,967			26,967		32,525
Variable Interest Entity, Not Primary Beneficiary | Other Assets
Variable Interest Entity [Line Items]
Total assets	$ 27,000			$ 27,000		$ 29,300
Variable Interest Entity, Not Primary Beneficiary | Multifamily
Variable Interest Entity [Line Items]
Funding transferred		$ 573,500
Credit losses guaranteed (percent)	12.00%			12.00%
Repurchase liability recognized	$ 3,500			$ 3,500
Maximum loss exposure	$ 68,800			$ 68,800