USE OF DERIVATIVES, OFFSETTING DISCLOSURES AND CHANGES IN OTHER COMPREHENSIVE INCOME BY COMPONENT, Changes in AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			$ 1,298,324
Other comprehensive income (loss) before reclassifications	$ (5,228)		(24,872)
Amounts reclassified from accumulated other comprehensive income	5,826		11,180
Other comprehensive income (loss)	598	$ (8,484)	(13,692)	$ (14,320)
Ending Balance	1,281,122		1,281,122
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	121,805		136,095
Ending Balance	122,403		122,403
Gains and Losses on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(45,207)		(18,434)
Other comprehensive income (loss) before reclassifications	(22,145)		(54,272)
Amounts reclassified from accumulated other comprehensive income	5,826		11,180
Other comprehensive income (loss)	(16,319)		(43,092)
Ending Balance	(61,526)		(61,526)
Unrealized Gains and Losses on Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	167,012		154,529
Other comprehensive income (loss) before reclassifications	16,917		29,400
Amounts reclassified from accumulated other comprehensive income	0		0
Other comprehensive income (loss)	16,917		29,400
Ending Balance	$ 183,929		$ 183,929