Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 761,920	$ 631,355	$ 1,496,114	$ 1,193,905
U.S. Drilling
Disaggregation of Revenue [Line Items]
Revenue	264,395	187,344	505,397	349,278
Canada Drilling
Disaggregation of Revenue [Line Items]
Revenue	17,442	17,121	49,329	44,929
International Drilling
Disaggregation of Revenue [Line Items]
Revenue	377,986	380,338	746,831	718,561
Drilling Solutions
Disaggregation of Revenue [Line Items]
Revenue	(59,859)	31,829	122,507	59,194
Rig Technologies
Disaggregation of Revenue [Line Items]
Revenue	81,321	61,185	145,990	105,261
Other
Disaggregation of Revenue [Line Items]
Revenue	(39,083)	46,462	(73,940)	(83,318)
Operating segment | Lower 48
Disaggregation of Revenue [Line Items]
Revenue	318,380	243,230	617,842	441,433
Operating segment | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Revenue	34,874	16,462	59,164	29,853
Operating segment | Alaska
Disaggregation of Revenue [Line Items]
Revenue	14,027	12,351	30,148	25,013
Operating segment | Canada
Disaggregation of Revenue [Line Items]
Revenue	29,089	20,007	66,656	51,773
Operating segment | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue	256,018	226,951	502,811	427,826
Operating segment | Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenue	93,393	104,534	182,917	198,494
Operating segment | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Revenue	55,222	54,282	110,516	102,831
Operating segment | U.S. Drilling
Disaggregation of Revenue [Line Items]
Revenue	264,395	187,344	505,397	349,278
Operating segment | U.S. Drilling | Lower 48
Disaggregation of Revenue [Line Items]
Revenue	219,389	160,126	423,981	297,349
Operating segment | U.S. Drilling | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Revenue	32,064	16,361	53,055	29,667
Operating segment | U.S. Drilling | Alaska
Disaggregation of Revenue [Line Items]
Revenue	12,942	10,857	28,361	22,262
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Revenue	17,442	17,121	49,329	44,929
Operating segment | Canada Drilling | Canada
Disaggregation of Revenue [Line Items]
Revenue	17,442	17,121	49,329	44,929
Operating segment | International Drilling
Disaggregation of Revenue [Line Items]
Revenue	377,986	380,338	746,831	718,561
Operating segment | International Drilling | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue	240,508	222,294	474,367	418,552
Operating segment | International Drilling | Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenue	87,809	103,920	171,691	197,365
Operating segment | International Drilling | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Revenue	49,669	54,124	100,773	102,644
Operating segment | Drilling Solutions
Disaggregation of Revenue [Line Items]
Revenue	59,859	31,829	122,507	59,194
Operating segment | Drilling Solutions | Lower 48
Disaggregation of Revenue [Line Items]
Revenue	41,418	26,509	85,687	48,829
Operating segment | Drilling Solutions | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Revenue	2,810	101	6,109	186
Operating segment | Drilling Solutions | Alaska
Disaggregation of Revenue [Line Items]
Revenue	877	1,306	1,443	2,437
Operating segment | Drilling Solutions | Canada
Disaggregation of Revenue [Line Items]
Revenue	1,425	1,322	3,716	3,305
Operating segment | Drilling Solutions | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue	9,007	1,819	16,735	3,121
Operating segment | Drilling Solutions | Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenue	3,665	614	7,649	1,129
Operating segment | Drilling Solutions | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Revenue	657	158	1,168	187
Operating segment | Rig Technologies
Disaggregation of Revenue [Line Items]
Revenue	81,321	61,185	145,990	105,261
Operating segment | Rig Technologies | Lower 48
Disaggregation of Revenue [Line Items]
Revenue	57,573	56,595	108,174	95,255
Operating segment | Rig Technologies | Alaska
Disaggregation of Revenue [Line Items]
Revenue	208	188	344	314
Operating segment | Rig Technologies | Canada
Disaggregation of Revenue [Line Items]
Revenue	10,222	1,564	13,611	3,539
Operating segment | Rig Technologies | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Revenue	6,503	2,838	11,709	6,153
Operating segment | Rig Technologies | Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,919		3,577
Operating segment | Rig Technologies | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Revenue	4,896		8,575
Other reconciling items (1) | Other
Disaggregation of Revenue [Line Items]
Revenue	(39,083)	(46,462)	(73,940)	(83,318)
Other reconciling items (1) | Other | Other
Disaggregation of Revenue [Line Items]
Revenue	(39,083)	46,462	(73,940)	(83,318)
Other reconciling items (3)
Disaggregation of Revenue [Line Items]
Revenue	$ 39,083	$ 46,462	$ 73,940	$ 83,318