Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Operating revenues	$ 718,364	$ 799,640
U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	274,901	320,209
Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	25,591	25,315
International Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	337,110	337,256
Drilling Solutions
Disaggregation of Revenue [Line Items]
Operating revenues	55,384	65,422
Rig Technologies
Disaggregation of Revenue [Line Items]
Operating revenues	42,150	71,753
Other
Disaggregation of Revenue [Line Items]
Operating revenues	(16,772)	(20,315)
Operating segment | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	276,475	357,658
Operating segment | Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues	42,221	45,725
Operating segment | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	16,593	21,888
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	27,932	28,616
Operating segment | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	227,768	209,075
Operating segment | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	87,198	96,517
Operating segment | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	56,949	60,476
Operating segment | U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	274,901	320,209
Operating segment | U.S. Drilling | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	220,229	258,871
Operating segment | U.S. Drilling | Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues	39,056	41,481
Operating segment | U.S. Drilling | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	15,616	19,857
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	25,591	25,315
Operating segment | Canada Drilling | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	25,591	25,315
Operating segment | International Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	337,110	337,256
Operating segment | International Drilling | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	201,177	187,969
Operating segment | International Drilling | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	84,219	92,366
Operating segment | International Drilling | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	51,714	56,921
Operating segment | Drilling Solutions
Disaggregation of Revenue [Line Items]
Operating revenues	55,384	65,422
Operating segment | Drilling Solutions | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	35,715	44,052
Operating segment | Drilling Solutions | Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues	3,165	4,244
Operating segment | Drilling Solutions | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	986	1,728
Operating segment | Drilling Solutions | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	729	673
Operating segment | Drilling Solutions | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	11,037	10,505
Operating segment | Drilling Solutions | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	2,827	3,231
Operating segment | Drilling Solutions | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	925	989
Operating segment | Rig Technologies
Disaggregation of Revenue [Line Items]
Operating revenues	42,150	71,753
Operating segment | Rig Technologies | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	20,531	54,735
Operating segment | Rig Technologies | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	(9)	303
Operating segment | Rig Technologies | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	1,612	2,628
Operating segment | Rig Technologies | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	15,554	10,601
Operating segment | Rig Technologies | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues	152	920
Operating segment | Rig Technologies | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	4,310	2,566
Other reconciling items (1) | Other
Disaggregation of Revenue [Line Items]
Operating revenues	(16,772)	(20,315)
Other reconciling items (1) | Other | Other
Disaggregation of Revenue [Line Items]
Operating revenues	(16,772)	(20,315)
Other reconciling items (3)
Disaggregation of Revenue [Line Items]
Operating revenues	$ 16,772	$ 20,315