Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 779,425	$ 662,103	$ 2,275,539	$ 1,856,008
U.S. Drilling
Disaggregation of Revenue [Line Items]
Revenue	273,996	222,747	779,393	572,025
Canada Drilling
Disaggregation of Revenue [Line Items]
Revenue	26,645	18,073	75,974	63,002
International Drilling
Disaggregation of Revenue [Line Items]
Revenue	377,125	374,106	1,123,956	1,092,667
Drilling Solutions
Disaggregation of Revenue [Line Items]
Revenue	(60,923)	37,506	183,430	96,700
Rig Technologies
Disaggregation of Revenue [Line Items]
Revenue	63,641	50,032	209,631	155,293
Other
Disaggregation of Revenue [Line Items]
Revenue	(22,905)	40,361	(96,845)	(123,679)
Operating segment | Lower 48
Disaggregation of Revenue [Line Items]
Revenue	319,687	266,971	937,527	708,405
Operating segment | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Revenue	35,287	21,397	94,452	51,250
Operating segment | Alaska
Disaggregation of Revenue [Line Items]
Revenue	11,576	13,799	41,724	38,811
Operating segment | Canada
Disaggregation of Revenue [Line Items]
Revenue	31,209	20,875	97,867	72,648
Operating segment | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue	243,934	223,836	746,743	651,663
Operating segment | Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenue	99,051	100,334	281,967	298,829
Operating segment | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Revenue	61,586	55,252	172,104	158,081
Operating segment | U.S. Drilling
Disaggregation of Revenue [Line Items]
Revenue	273,996	222,747	779,393	572,025
Operating segment | U.S. Drilling | Lower 48
Disaggregation of Revenue [Line Items]
Revenue	231,935	188,947	655,916	486,297
Operating segment | U.S. Drilling | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Revenue	31,942	21,209	84,997	50,876
Operating segment | U.S. Drilling | Alaska
Disaggregation of Revenue [Line Items]
Revenue	10,119	12,591	38,480	34,852
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Revenue	26,645	18,073	75,974	63,002
Operating segment | Canada Drilling | Canada
Disaggregation of Revenue [Line Items]
Revenue	26,645	18,073	75,974	63,002
Operating segment | International Drilling
Disaggregation of Revenue [Line Items]
Revenue	377,125	374,106	1,123,956	1,092,667
Operating segment | International Drilling | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue	226,926	219,494	701,292	638,047
Operating segment | International Drilling | Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenue	94,048	99,585	265,738	296,950
Operating segment | International Drilling | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Revenue	56,151	55,027	156,926	157,670
Operating segment | Drilling Solutions
Disaggregation of Revenue [Line Items]
Revenue	60,923	37,506	183,430	96,700
Operating segment | Drilling Solutions | Lower 48
Disaggregation of Revenue [Line Items]
Revenue	42,045	32,649	127,733	81,478
Operating segment | Drilling Solutions | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Revenue	3,345	188	9,455	374
Operating segment | Drilling Solutions | Alaska
Disaggregation of Revenue [Line Items]
Revenue	1,248	1,021	2,691	3,457
Operating segment | Drilling Solutions | Canada
Disaggregation of Revenue [Line Items]
Revenue	1,081	1,303	4,797	4,608
Operating segment | Drilling Solutions | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue	9,126	1,461	25,859	4,583
Operating segment | Drilling Solutions | Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenue	3,399	749	11,048	1,879
Operating segment | Drilling Solutions | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Revenue	679	135	1,847	321
Operating segment | Rig Technologies
Disaggregation of Revenue [Line Items]
Revenue	63,641	50,032	209,631	155,293
Operating segment | Rig Technologies | Lower 48
Disaggregation of Revenue [Line Items]
Revenue	45,707	45,375	153,878	140,630
Operating segment | Rig Technologies | Alaska
Disaggregation of Revenue [Line Items]
Revenue	209	187	553	502
Operating segment | Rig Technologies | Canada
Disaggregation of Revenue [Line Items]
Revenue	3,483	1,499	17,096	5,038
Operating segment | Rig Technologies | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue	7,882	2,881	19,592	9,033
Operating segment | Rig Technologies | Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,604		5,181
Operating segment | Rig Technologies | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Revenue	4,756	90	13,331	90
Other reconciling items (1) | Other
Disaggregation of Revenue [Line Items]
Revenue	(22,905)	(40,361)	(96,845)	(123,679)
Other reconciling items (1) | Other | Other
Disaggregation of Revenue [Line Items]
Revenue	(22,905)	40,361	(96,845)	(123,679)
Other reconciling items (3)
Disaggregation of Revenue [Line Items]
Revenue	$ 22,905	$ 40,361	$ 96,845	$ 123,679