Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Accrued Liabilities
Capital expenditures	$ 26,590	$ 35,608
Operating expenses	16,715	14,582
Interest	1,761	10,613
Other	2,017	838
Accrued liabilities	$ 47,083	$ 61,641