Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 734,194	$ 562,550
U.S. Drilling
Disaggregation of Revenue [Line Items]
Revenue	241,002	161,934
Canada Drilling
Disaggregation of Revenue [Line Items]
Revenue	31,887	27,808
International Drilling
Disaggregation of Revenue [Line Items]
Revenue	368,845	338,223
Drilling Solutions
Disaggregation of Revenue [Line Items]
Revenue	(62,648)	27,365
Rig Technologies
Disaggregation of Revenue [Line Items]
Revenue	64,669	44,076
Other
Disaggregation of Revenue [Line Items]
Revenue	(34,857)	36,856
Operating segment | Lower 48
Disaggregation of Revenue [Line Items]
Revenue	299,462	198,200
Operating segment | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Revenue	24,290	13,391
Operating segment | Alaska
Disaggregation of Revenue [Line Items]
Revenue	16,121	12,662
Operating segment | Canada
Disaggregation of Revenue [Line Items]
Revenue	37,568	31,767
Operating segment | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue	246,790	200,878
Operating segment | Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenue	89,525	93,960
Operating segment | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Revenue	55,295	48,548
Operating segment | U.S. Drilling
Disaggregation of Revenue [Line Items]
Revenue	241,002	161,934
Operating segment | U.S. Drilling | Lower 48
Disaggregation of Revenue [Line Items]
Revenue	204,592	137,223
Operating segment | U.S. Drilling | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Revenue	20,991	13,306
Operating segment | U.S. Drilling | Alaska
Disaggregation of Revenue [Line Items]
Revenue	15,419	11,405
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Revenue	31,887	27,808
Operating segment | Canada Drilling | Canada
Disaggregation of Revenue [Line Items]
Revenue	31,887	27,808
Operating segment | International Drilling
Disaggregation of Revenue [Line Items]
Revenue	368,845	338,223
Operating segment | International Drilling | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue	233,857	196,260
Operating segment | International Drilling | Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenue	83,883	93,444
Operating segment | International Drilling | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Revenue	51,105	48,519
Operating segment | Drilling Solutions
Disaggregation of Revenue [Line Items]
Revenue	62,648	27,365
Operating segment | Drilling Solutions | Lower 48
Disaggregation of Revenue [Line Items]
Revenue	44,273	22,318
Operating segment | Drilling Solutions | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Revenue	3,299	85
Operating segment | Drilling Solutions | Alaska
Disaggregation of Revenue [Line Items]
Revenue	566	1,131
Operating segment | Drilling Solutions | Canada
Disaggregation of Revenue [Line Items]
Revenue	2,290	1,983
Operating segment | Drilling Solutions | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue	7,725	1,303
Operating segment | Drilling Solutions | Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenue	3,984	516
Operating segment | Drilling Solutions | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Revenue	511	29
Operating segment | Rig Technologies
Disaggregation of Revenue [Line Items]
Revenue	64,669	44,076
Operating segment | Rig Technologies | Lower 48
Disaggregation of Revenue [Line Items]
Revenue	50,597	38,659
Operating segment | Rig Technologies | Alaska
Disaggregation of Revenue [Line Items]
Revenue	136	126
Operating segment | Rig Technologies | Canada
Disaggregation of Revenue [Line Items]
Revenue	3,391	1,976
Operating segment | Rig Technologies | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue	5,208	3,315
Operating segment | Rig Technologies | Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,658
Operating segment | Rig Technologies | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Revenue	3,679
Other reconciling items (1) | Other
Disaggregation of Revenue [Line Items]
Revenue	(34,857)	(36,856)
Other reconciling items (1) | Other | Other
Disaggregation of Revenue [Line Items]
Revenue	(34,857)	36,856
Other reconciling items (3)
Disaggregation of Revenue [Line Items]
Revenue	$ 34,857	$ 36,856