Income Taxes - Deferred Tax Assets And Liabilities Due To Temporary Differences (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Taxes
Reserve for receivables, noncurrent	$ 564	$ 667
Accrued liabilities and inventory reserves, noncurrent	6,358	7,472
Net operating loss carryforward, non-current	12,940	8,779
Unrealized loss on derivative instruments, non-current	70	5,452
Share-based compensation, non-current	5,859	11,455
Asset retirement obligations, non-current	2,595	3,300
Tangible and intangible assets, non-current	25,117	13,343
Deferred revenue, non-current	287	878
Other, non-current	6,745	3,340
Subtotal, non-current	60,535	54,686
Valuation allowance	(9,545)	(3,094)
Non-current deferred tax assets	50,990	51,592
Tangible and intangible assets, non-current	(79,666)	(66,116)
Asset retirement obligations, non-current	(45)	(97)
Unrealized loss on interst rate swap contracts	(1,181)
Other, noncurrrent	(303)
Non-current deferred tax liability	(81,195)	(66,213)
Net deferred tax liability	$ (30,205)	$ (14,621)