Summary of Significant Accounting Policies - Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment
Value of shares sold	$ 301,404	$ 8,300	$ 967
Loss on sale of offshore rigs	$ 11,789	$ 19,026	$ 14,830
Rig Assets Excluding Jackup Rigs
Property, Plant and Equipment
Operating rig asset depreciable life, operating days	4927 days
Non-operating rig asset depreciable life	20 years
Jack Up Rigs
Property, Plant and Equipment
Operating rig asset depreciable life, operating days	8030 days
Non-operating rig asset depreciable life	30 years
Buildings | Minimum
Property, Plant and Equipment
Estimated useful life	10 years
Buildings | Maximum
Property, Plant and Equipment
Estimated useful life	30 years
Oilfield Hauling and Mobile Equipment and Other Machinery and Equipment | Minimum
Property, Plant and Equipment
Estimated useful life	3 years
Oilfield Hauling and Mobile Equipment and Other Machinery and Equipment | Maximum
Property, Plant and Equipment
Estimated useful life	10 years