Nature of Operations and Recent Events - Assets Held For Sale (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Gain) loss on disposition of assets, net	$ (260)		$ 0		$ (675)	$ 1,573
Corporate Headquarters And Rig Assembly Yard | Disposal Group, Held-for-sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property, plant and equipment classified as held for sale				$ 4,000
(Gain) loss on disposition of assets, net		$ (208)	$ 600	$ 500
Increase (decrease) in assets held-for-sale		(2,700)
Increase (decrease) to property, plant and equipment		$ 2,900
Galayda Facility | Disposal Group, Held-for-sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Gain) loss on disposition of assets, net	650
Increase (decrease) in assets held-for-sale	2,600
Disposal group, including discontinued operation, consideration	$ 3,100				$ 3,100