Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Operating revenues	$ 438,352	$ 758,076	$ 1,690,647	$ 2,329,122
U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	130,243	307,808	578,928	951,419
Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	10,774	12,191	39,929	48,895
International Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	248,392	328,278	886,580	992,439
Drilling Solutions
Disaggregation of Revenue [Line Items]
Operating revenues	29,324	62,286	117,837	192,291
Rig Technologies
Disaggregation of Revenue [Line Items]
Operating revenues	28,466	63,106	104,198	207,610
Other
Disaggregation of Revenue [Line Items]
Operating revenues	(8,847)	(15,593)	(36,825)	(63,532)
Operating segment | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	122,422	338,519	559,143	1,061,777
Operating segment | Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues	28,954	40,300	109,725	127,517
Operating segment | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	6,935	15,294	32,085	54,234
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	11,476	14,443	43,635	57,250
Operating segment | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	200,582	222,743	648,741	639,581
Operating segment | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	44,798	90,571	182,220	279,767
Operating segment | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	32,032	51,799	151,923	172,528
Operating segment | U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	130,243	307,808	578,928	951,419
Operating segment | U.S. Drilling | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	96,433	256,978	445,478	784,638
Operating segment | U.S. Drilling | Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues	26,943	37,365	102,681	117,572
Operating segment | U.S. Drilling | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	6,867	13,465	30,769	49,209
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	10,774	12,191	39,929	48,895
Operating segment | Canada Drilling | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	10,774	12,191	39,929	48,895
Operating segment | International Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	248,392	328,278	886,580	992,439
Operating segment | International Drilling | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	176,617	197,095	571,108	570,142
Operating segment | International Drilling | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	43,881	85,558	177,800	266,715
Operating segment | International Drilling | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	27,894	45,625	137,672	155,582
Operating segment | Drilling Solutions
Disaggregation of Revenue [Line Items]
Operating revenues	29,324	62,286	117,837	192,291
Operating segment | Drilling Solutions | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	15,769	41,459	70,805	132,156
Operating segment | Drilling Solutions | Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues	2,011	2,935	7,044	9,945
Operating segment | Drilling Solutions | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	66	1,488	1,296	4,137
Operating segment | Drilling Solutions | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	187	358	995	1,413
Operating segment | Drilling Solutions | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	10,096	11,167	31,630	31,095
Operating segment | Drilling Solutions | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	902	4,545	4,284	11,202
Operating segment | Drilling Solutions | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	293	334	1,783	2,343
Operating segment | Rig Technologies
Disaggregation of Revenue [Line Items]
Operating revenues	28,466	63,106	104,198	207,610
Operating segment | Rig Technologies | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	10,220	40,082	42,860	144,983
Operating segment | Rig Technologies | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	2	341	20	888
Operating segment | Rig Technologies | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	515	1,894	2,711	6,942
Operating segment | Rig Technologies | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	13,869	14,481	46,003	38,344
Operating segment | Rig Technologies | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	15	468	136	1,850
Operating segment | Rig Technologies | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	3,845	5,840	12,468	14,603
Other reconciling items (1) | Other
Disaggregation of Revenue [Line Items]
Operating revenues	(8,847)	(15,593)	(36,825)	(63,532)
Other reconciling items (1) | Other | Other
Disaggregation of Revenue [Line Items]
Operating revenues	(8,847)	(15,593)	(36,825)	(63,532)
Other reconciling items (3)
Disaggregation of Revenue [Line Items]
Operating revenues	$ 8,847	$ 15,593	$ 36,825	$ 63,532