Details of Certain Accounts - Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued payroll and related benefits	$ 14,775	$ 61,246
Current asset retirement obligations	553	575
Unearned revenue	12,841	11,461
Accrued interest	4,854	4,221
Derivative liability (Note 18)	23,192	13,222
Taxes payable excluding income tax payable	8,136	6,236
Other	7,290	7,962
Total accrued liabilities	$ 71,641	$ 104,923