Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Operating revenues	$ 489,333	$ 533,931	$ 949,844	$ 1,252,295
U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	161,606	173,784	303,905	448,685
Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	12,313	3,564	33,302	29,155
International Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	255,282	301,078	502,120	638,188
Drilling Solutions
Disaggregation of Revenue [Line Items]
Operating revenues	39,111	33,129	74,817	88,513
Rig Technologies
Disaggregation of Revenue [Line Items]
Operating revenues	34,552	33,582	60,300	75,732
Other
Disaggregation of Revenue [Line Items]
Operating revenues	(13,531)	(11,206)	(24,600)	(27,978)
Operating segment | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	158,244	160,247	298,765	436,720
Operating segment | U.S. Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues	34,789	38,549	64,717	80,771
Operating segment | Alaska
Disaggregation of Revenue [Line Items]
Operating revenues	7,478	8,559	13,186	25,152
Operating segment | Canada
Disaggregation of Revenue [Line Items]
Operating revenues	13,900	4,226	36,243	32,159
Operating segment | Middle East & Asia
Disaggregation of Revenue [Line Items]
Operating revenues	197,371	220,390	383,628	448,158
Operating segment | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	63,752	50,225	124,239	137,423
Operating segment | Europe, Africa & CIS
Disaggregation of Revenue [Line Items]
Operating revenues	27,330	62,941	53,666	119,890
Operating segment | U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	161,606	173,784	303,905	448,685
Operating segment | U.S. Drilling | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	121,360	128,814	230,896	349,043
Operating segment | U.S. Drilling | U.S. Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues	32,967	36,682	60,159	75,738
Operating segment | U.S. Drilling | Alaska
Disaggregation of Revenue [Line Items]
Operating revenues	7,279	8,288	12,850	23,904
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	12,313	3,564	33,302	29,155
Operating segment | Canada Drilling | Canada
Disaggregation of Revenue [Line Items]
Operating revenues	12,313	3,564	33,302	29,155
Operating segment | International Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	255,282	301,078	502,120	638,188
Operating segment | International Drilling | Middle East & Asia
Disaggregation of Revenue [Line Items]
Operating revenues	174,339	193,313	342,525	394,490
Operating segment | International Drilling | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	57,931	49,700	113,839	133,919
Operating segment | International Drilling | Europe, Africa & CIS
Disaggregation of Revenue [Line Items]
Operating revenues	23,012	58,065	45,756	109,779
Operating segment | Drilling Solutions
Disaggregation of Revenue [Line Items]
Operating revenues	39,111	33,129	74,817	88,513
Operating segment | Drilling Solutions | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	21,436	19,325	39,884	55,037
Operating segment | Drilling Solutions | U.S. Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues	1,822	1,867	4,558	5,033
Operating segment | Drilling Solutions | Alaska
Disaggregation of Revenue [Line Items]
Operating revenues	185	244	322	1,230
Operating segment | Drilling Solutions | Canada
Disaggregation of Revenue [Line Items]
Operating revenues	204	78	658	808
Operating segment | Drilling Solutions | Middle East & Asia
Disaggregation of Revenue [Line Items]
Operating revenues	9,457	10,496	18,448	21,534
Operating segment | Drilling Solutions | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	5,658	555	10,224	3,382
Operating segment | Drilling Solutions | Europe, Africa & CIS
Disaggregation of Revenue [Line Items]
Operating revenues	349	564	723	1,489
Operating segment | Rig Technologies
Disaggregation of Revenue [Line Items]
Operating revenues	34,552	33,582	60,300	75,732
Operating segment | Rig Technologies | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	15,448	12,108	27,985	32,640
Operating segment | Rig Technologies | Alaska
Disaggregation of Revenue [Line Items]
Operating revenues	14	27	14	18
Operating segment | Rig Technologies | Canada
Disaggregation of Revenue [Line Items]
Operating revenues	1,383	584	2,283	2,196
Operating segment | Rig Technologies | Middle East & Asia
Disaggregation of Revenue [Line Items]
Operating revenues	13,575	16,581	22,655	32,134
Operating segment | Rig Technologies | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	163	(30)	176	122
Operating segment | Rig Technologies | Europe, Africa & CIS
Disaggregation of Revenue [Line Items]
Operating revenues	3,969	4,312	7,187	8,622
Other reconciling items | Other
Disaggregation of Revenue [Line Items]
Operating revenues	(13,531)	(11,206)	(24,600)	(27,978)
Other reconciling items | Other | Other
Disaggregation of Revenue [Line Items]
Operating revenues	(13,531)	(11,206)	(24,600)	(27,978)
Other reconciling items (3)
Disaggregation of Revenue [Line Items]
Operating revenues	$ 13,531	$ 11,206	$ 24,600	$ 27,978