Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Operating revenues	$ 758,076	$ 779,425	$ 2,329,122	$ 2,275,539
U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	307,808	273,996	951,419	779,393
Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	12,191	26,645	48,895	75,974
International Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	328,278	377,125	992,439	1,123,956
Drilling Solutions
Disaggregation of Revenue [Line Items]
Operating revenues	62,286	60,923	192,291	183,430
Rig Technologies
Disaggregation of Revenue [Line Items]
Operating revenues	63,106	63,641	207,610	209,631
Other
Disaggregation of Revenue [Line Items]
Operating revenues	(15,593)	(22,905)	(63,532)	(96,845)
Operating segment | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	338,519	319,687	1,061,777	937,527
Operating segment | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	40,300	35,287	127,517	94,452
Operating segment | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	15,294	11,576	54,234	41,724
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	14,443	31,209	57,250	97,867
Operating segment | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	222,743	243,934	639,581	746,743
Operating segment | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	90,571	99,051	279,767	281,967
Operating segment | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	51,799	61,586	172,528	172,104
Operating segment | U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	307,808	273,996	951,419	779,393
Operating segment | U.S. Drilling | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	256,978	231,935	784,638	655,916
Operating segment | U.S. Drilling | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	37,365	31,942	117,572	84,997
Operating segment | U.S. Drilling | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	13,465	10,119	49,209	38,480
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	12,191	26,645	48,895	75,974
Operating segment | Canada Drilling | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	12,191	26,645	48,895	75,974
Operating segment | International Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	328,278	377,125	992,439	1,123,956
Operating segment | International Drilling | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	197,095	226,926	570,142	701,292
Operating segment | International Drilling | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	85,558	94,048	266,715	265,738
Operating segment | International Drilling | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	45,625	56,151	155,582	156,926
Operating segment | Drilling Solutions
Disaggregation of Revenue [Line Items]
Operating revenues	62,286	60,923	192,291	183,430
Operating segment | Drilling Solutions | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	41,459	42,045	132,156	127,733
Operating segment | Drilling Solutions | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	2,935	3,345	9,945	9,455
Operating segment | Drilling Solutions | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	1,488	1,248	4,137	2,691
Operating segment | Drilling Solutions | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	358	1,081	1,413	4,797
Operating segment | Drilling Solutions | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	11,167	9,126	31,095	25,859
Operating segment | Drilling Solutions | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	4,545	3,399	11,202	11,048
Operating segment | Drilling Solutions | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	334	679	2,343	1,847
Operating segment | Rig Technologies
Disaggregation of Revenue [Line Items]
Operating revenues	63,106	63,641	207,610	209,631
Operating segment | Rig Technologies | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	40,082	45,707	144,983	153,878
Operating segment | Rig Technologies | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	341	209	888	553
Operating segment | Rig Technologies | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	1,894	3,483	6,942	17,096
Operating segment | Rig Technologies | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	14,481	7,882	38,344	19,592
Operating segment | Rig Technologies | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	468	1,604	1,850	5,181
Operating segment | Rig Technologies | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	5,840	4,756	14,603	13,331
Other reconciling items (1) | Other
Disaggregation of Revenue [Line Items]
Operating revenues	(15,593)	(22,905)	(63,532)	(96,845)
Other reconciling items (1) | Other | Other
Disaggregation of Revenue [Line Items]
Operating revenues	(15,593)	(22,905)	(63,532)	(96,845)
Other reconciling items (3)
Disaggregation of Revenue [Line Items]
Operating revenues	$ 15,593	$ 22,905	$ 63,532	$ 96,845