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
	Mar. 31, 2017	Mar. 31, 2016
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	$ 1,247,687
Other comprehensive income (loss) before reclassifications	12,092
Amounts reclassified from accumulated other comprehensive income	1,661
Other comprehensive income (loss)	13,753	$ (14,290)
Ending Balance	1,260,705
Gains and Losses on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	151
Other comprehensive income (loss) before reclassifications	8,096
Amounts reclassified from accumulated other comprehensive income	1,661
Other comprehensive income (loss)	9,757
Ending Balance	9,908
Unrealized Gains and Losses on Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	105,635
Other comprehensive income (loss) before reclassifications	3,996
Amounts reclassified from accumulated other comprehensive income	0
Other comprehensive income (loss)	3,996
Ending Balance	109,631
Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	105,786
Ending Balance	$ 119,539