Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accrued Liabilities
Accrued capital expenditures	$ 162,116	$ 159,811
Accrued gathering, compression, processing, and transportation expenses	84,388	75,223
Accrued marketing expenses	32,455	52,822
Accrued interest expense	66,398	35,533
Other accrued liabilities	84,339	70,414
Total accrued liabilities	$ 429,696	$ 393,803