Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Accounts payable and accrued liabilities
Accounts payable	$ 176,069	$ 209,527
Accrued compensation and benefits	38,020	42,485
Accrued interest	12,147	19,748
Other accrued expenses	45,662	49,553
Total	$ 271,898	$ 321,313