USE OF DERIVATIVES, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 1,059,063	$ 1,238,876	$ 1,247,687
Other comprehensive income (loss)	34,445	(83,164)	(43,773)
Ending Balance	1,073,733	1,059,063	1,238,876
Unrealized Gains and Losses on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	6,200	16,874	151
Other comprehensive income (loss) before reclassifications	(17,080)	25,716	21,426
Amounts reclassified from accumulated other comprehensive income	(20,988)	(36,390)	(4,808)
Cumulative effect adjustment			105
Other comprehensive income (loss)	(38,068)	(10,674)	16,723
Ending Balance	(31,868)	6,200	16,874
Unrealized Gains and Losses on Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(27,246)	45,244	105,635
Other comprehensive income (loss) before reclassifications	71,148	(72,490)	(60,391)
Amounts reclassified from accumulated other comprehensive income	1,365	0	0
Cumulative effect adjustment			0
Other comprehensive income (loss)	72,513	(72,490)	(60,391)
Ending Balance	45,267	(27,246)	45,244
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(21,046)	62,118	105,786
Other comprehensive income (loss) before reclassifications	54,068	(46,774)	(38,965)
Amounts reclassified from accumulated other comprehensive income	(19,623)	(36,390)	(4,808)
Cumulative effect adjustment			105
Other comprehensive income (loss)	34,445	(83,164)	(43,668)
Ending Balance	$ 13,399	$ (21,046)	$ 62,118