USE OF DERIVATIVES, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 1,073,733	$ 1,059,063	$ 1,238,876
Other comprehensive income (loss)	27,485	34,445	(83,164)
Ending Balance	910,163	1,073,733	1,059,063
Unrealized Gains and Losses on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(31,868)	6,200	16,874
Other comprehensive income (loss) before reclassifications	(15,621)	(17,080)	25,716
Amounts reclassified from accumulated other comprehensive income	3,822	(20,988)	(36,390)
Other comprehensive income (loss)	(11,799)	(38,068)	(10,674)
Ending Balance	(43,667)	(31,868)	6,200
Unrealized Gains and Losses on Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	45,267	(27,246)	45,244
Other comprehensive income (loss) before reclassifications	(27,580)	71,148	(72,490)
Amounts reclassified from accumulated other comprehensive income	66,864	1,365	0
Other comprehensive income (loss)	39,284	72,513	(72,490)
Ending Balance	84,551	45,267	(27,246)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	13,399	(21,046)	62,118
Other comprehensive income (loss) before reclassifications	(43,201)	54,068	(46,774)
Amounts reclassified from accumulated other comprehensive income	70,686	(19,623)	(36,390)
Other comprehensive income (loss)	27,485	34,445	(83,164)
Ending Balance	$ 40,884	$ 13,399	$ (21,046)