USE OF DERIVATIVES, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			$ 1,238,876
Other comprehensive (loss) income	$ (18,610)	$ (18,562)	(36,374)	$ (4,809)
Ending Balance	1,168,856		1,168,856
Unrealized Gains and Losses on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	43,163		16,874
Other comprehensive income (loss) before reclassifications	7,873		38,805
Amounts reclassified from accumulated other comprehensive income	(9,971)		(14,614)
Other comprehensive (loss) income	(2,098)		24,191
Ending Balance	41,065		41,065
Unrealized Gains and Losses on Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	1,191		45,244
Other comprehensive income (loss) before reclassifications	(16,512)		(60,565)
Amounts reclassified from accumulated other comprehensive income	0		0
Other comprehensive (loss) income	(16,512)		(60,565)
Ending Balance	(15,321)		(15,321)
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	44,354		62,118
Other comprehensive income (loss) before reclassifications	(8,639)		(21,760)
Amounts reclassified from accumulated other comprehensive income	(9,971)		(14,614)
Other comprehensive (loss) income	(18,610)		(36,374)
Ending Balance	$ 25,744		$ 25,744