USE OF DERIVATIVES, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME (LOSS) BY COMPONENT - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 1,073,733	$ 1,059,063
Other comprehensive income	(19,677)	24,354
Ending Balance	843,624	1,064,878
Unrealized Gains and Losses on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(31,868)
Other comprehensive loss before reclassifications	(21,251)
Amounts reclassified from accumulated other comprehensive income (loss)	480
Other comprehensive income	(20,771)
Ending Balance	(52,639)
Unrealized Gains and Losses on Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	45,267
Other comprehensive loss before reclassifications	(65,770)
Amounts reclassified from accumulated other comprehensive income (loss)	66,864
Other comprehensive income	1,094
Ending Balance	46,361
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	13,399	(21,046)
Other comprehensive loss before reclassifications	(87,021)
Amounts reclassified from accumulated other comprehensive income (loss)	67,344
Other comprehensive income	(19,677)
Ending Balance	$ (6,278)	$ 3,308