Summary of Significant Accounting Policies - Goodwill (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Change in the carrying amount of goodwill for various contract drilling segments and other operating segments
Goodwill - Beginning Balance	$ 166,917,000	$ 166,659,000
Acquisitions and purchase price adjustment	5,690,000
Cumulative Translation Adjustment	619,000	258,000
Goodwill - Ending Balance	$ 173,226,000	166,917,000
Goodwill
Long-term growth rate used to calculate terminal values for each reporting unit (as a percent)	3.00%
Discontinued Operation, additional disclosures
Goodwill for the consolidated company, expected to be deductible for tax purposes	$ 10,200,000
United States
Change in the carrying amount of goodwill for various contract drilling segments and other operating segments
Goodwill - Beginning Balance	50,149,000	50,149,000
Goodwill - Ending Balance	50,149,000	50,149,000
International
Change in the carrying amount of goodwill for various contract drilling segments and other operating segments
Goodwill - Beginning Balance	75,634,000	75,634,000
Goodwill - Ending Balance	75,634,000	75,634,000
Rig Technologies
Change in the carrying amount of goodwill for various contract drilling segments and other operating segments
Goodwill - Beginning Balance	41,134,000	40,876,000
Acquisitions and purchase price adjustment	5,690,000
Cumulative Translation Adjustment	619,000	258,000
Goodwill - Ending Balance	$ 47,443,000	$ 41,134,000