Derivative Instruments and Hedging Activities (Details 2) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES [Abstract]
Derivative Assets, Fair Value, Gross Assets	$ 82,764	$ 37,034
Gross Amount of Eligible Offsetting Recognized Derivative Liabilities	0	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	82,764	37,034
Derivative Asset, Not Offset, Policy Election Deduction	(45,613)	(19,786)
Cash Collateral Received	(10,082)	(6,415)
Derivative Asset, Fair Value, Amount Offset Against Collateral	27,069	10,833
Derivative Liability, Fair Value, Gross Liability	(66,042)	(25,891)
Gross Amount of Eligible Offsetting Recognized Derivative Assets	0	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	(66,042)	(25,891)
Derivative Liability, Not Offset, Policy Election Deduction	45,613	19,786
Cash Collateral Paid	2,535	1,741
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ (17,894)	$ (4,364)