Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Operating revenues	$ 533,931	$ 771,406	$ 1,252,295	$ 1,571,046
U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	173,784	323,402	448,685	643,611
Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	3,564	11,389	29,155	36,704
International Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	301,078	326,905	638,188	664,161
Drilling Solutions
Disaggregation of Revenue [Line Items]
Operating revenues	33,129	64,583	88,513	130,005
Rig Technologies
Disaggregation of Revenue [Line Items]
Operating revenues	33,582	72,751	75,732	144,504
Other
Disaggregation of Revenue [Line Items]
Operating revenues	(11,206)	(27,624)	(27,978)	(47,939)
Operating segment | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	160,247	365,599	436,720	723,258
Operating segment | Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues	38,549	41,492	80,771	87,218
Operating segment | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	8,559	17,052	25,152	38,939
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	4,226	14,193	32,159	42,809
Operating segment | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	220,390	207,762	448,158	416,836
Operating segment | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	50,225	92,680	137,423	189,198
Operating segment | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	62,941	60,252	119,890	120,727
Operating segment | U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	173,784	323,402	448,685	643,611
Operating segment | U.S. Drilling | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	128,814	268,788	349,043	527,659
Operating segment | U.S. Drilling | Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues	36,682	38,727	75,738	80,208
Operating segment | U.S. Drilling | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	8,288	15,887	23,904	35,744
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	3,564	11,389	29,155	36,704
Operating segment | Canada Drilling | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	3,564	11,389	29,155	36,704
Operating segment | International Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	301,078	326,905	638,188	664,161
Operating segment | International Drilling | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	193,313	185,077	394,490	373,045
Operating segment | International Drilling | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	49,700	88,792	133,919	181,159
Operating segment | International Drilling | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	58,065	53,036	109,779	109,957
Operating segment | Drilling Solutions
Disaggregation of Revenue [Line Items]
Operating revenues	33,129	64,583	88,513	130,005
Operating segment | Drilling Solutions | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	19,325	46,649	55,037	90,697
Operating segment | Drilling Solutions | Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues	1,867	2,765	5,033	7,010
Operating segment | Drilling Solutions | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	244	921	1,230	2,649
Operating segment | Drilling Solutions | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	78	382	808	1,056
Operating segment | Drilling Solutions | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	10,496	9,422	21,534	19,929
Operating segment | Drilling Solutions | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	555	3,426	3,382	6,657
Operating segment | Drilling Solutions | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	564	1,018	1,489	2,007
Operating segment | Rig Technologies
Disaggregation of Revenue [Line Items]
Operating revenues	33,582	72,751	75,732	144,504
Operating segment | Rig Technologies | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	12,108	50,162	32,640	104,902
Operating segment | Rig Technologies | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	27	244	18	546
Operating segment | Rig Technologies | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	584	2,422	2,196	5,049
Operating segment | Rig Technologies | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	16,581	13,263	32,134	23,862
Operating segment | Rig Technologies | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	(30)	462	122	1,382
Operating segment | Rig Technologies | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	4,312	6,198	8,622	8,763
Other reconciling items (1) | Other
Disaggregation of Revenue [Line Items]
Operating revenues	(11,206)	(27,624)	(27,978)	(47,939)
Other reconciling items (1) | Other | Other
Disaggregation of Revenue [Line Items]
Operating revenues	(11,206)	(27,624)	(27,978)	(47,939)
Other reconciling items (3)
Disaggregation of Revenue [Line Items]
Operating revenues	$ 11,206	$ 27,624	$ 27,978	$ 47,939