Fair Value Measurements (Fair Value of Assets and Liabilities Measured on Recurring Basis) (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Derivative Assets
Derivative Asset	$ 15,585	$ 19,943
Derivative Liabilities
Derivative Liabilities	(4,290)
Total net assets	11,295	19,943
Level 2 [Member]
Derivative Assets
Derivative Asset	15,585	19,943
Derivative Liabilities
Derivative Liabilities	(4,290)
Total net assets	$ 11,295	$ 19,943