Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements (Fair Value of Assets and Liabilities Measured on Recurring Basis) (Details)

v3.3.1.900
Fair Value Measurements (Fair Value of Assets and Liabilities Measured on Recurring Basis) (Details) - USD ($)
$ in Thousands
Dec. 31, 2015
Dec. 31, 2014
Derivative Assets    
Derivative Assets, Current $ 19,943 $ 27,850
Derivative Liabilities    
Derivative Liabilities, Current   (1,249)
Fair Value, Net Asset 19,943 26,601
Level 2 [Member]    
Derivative Liabilities    
Fair Value, Net Asset 19,943 26,601
Current assets - Fair market value of derivatives [Member]    
Derivative Assets    
Derivative Assets, Current 19,943 27,850
Current assets - Fair market value of derivatives [Member] | Level 2 [Member]    
Derivative Assets    
Derivative Assets, Current $ 19,943 27,850
Current liabilities - Fair value of derivatives [Member]    
Derivative Liabilities    
Derivative Liabilities, Current   (1,249)
Current liabilities - Fair value of derivatives [Member] | Level 2 [Member]    
Derivative Liabilities    
Derivative Liabilities, Current   $ (1,249)