Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Operating revenues	$ 799,640	$ 734,194
U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	320,209	241,002
Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	25,315	31,887
International Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	337,256	368,845
Drilling Solutions
Disaggregation of Revenue [Line Items]
Operating revenues	65,422	62,648
Rig Technologies
Disaggregation of Revenue [Line Items]
Operating revenues	71,753	64,669
Other
Disaggregation of Revenue [Line Items]
Operating revenues	(20,315)	(34,857)
Operating segment | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	357,658	299,462
Operating segment | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	45,725	24,290
Operating segment | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	21,888	16,121
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	28,616	37,568
Operating segment | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	209,075	246,790
Operating segment | Latin America [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	96,517	89,525
Operating segment | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	60,476	55,295
Operating segment | U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	320,209	241,002
Operating segment | U.S. Drilling | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	258,871	204,592
Operating segment | U.S. Drilling | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	41,481	20,991
Operating segment | U.S. Drilling | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	19,857	15,419
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	25,315	31,887
Operating segment | Canada Drilling | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	25,315	31,887
Operating segment | International Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	337,256	368,845
Operating segment | International Drilling | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	187,969	233,857
Operating segment | International Drilling | Latin America [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	92,366	83,883
Operating segment | International Drilling | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	56,921	51,105
Operating segment | Drilling Solutions
Disaggregation of Revenue [Line Items]
Operating revenues	65,422	62,648
Operating segment | Drilling Solutions | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	44,052	44,273
Operating segment | Drilling Solutions | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	4,244	3,299
Operating segment | Drilling Solutions | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	1,728	566
Operating segment | Drilling Solutions | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	673	2,290
Operating segment | Drilling Solutions | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	10,505	7,725
Operating segment | Drilling Solutions | Latin America [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	3,231	3,984
Operating segment | Drilling Solutions | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	989	511
Operating segment | Rig Technologies
Disaggregation of Revenue [Line Items]
Operating revenues	71,753	64,669
Operating segment | Rig Technologies | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues	54,735	50,597
Operating segment | Rig Technologies | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues	303	136
Operating segment | Rig Technologies | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues	2,628	3,391
Operating segment | Rig Technologies | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	10,601	5,208
Operating segment | Rig Technologies | Latin America [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	920	1,658
Operating segment | Rig Technologies | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	2,566	3,679
Other reconciling items (1) | Other
Disaggregation of Revenue [Line Items]
Operating revenues	(20,315)	(34,857)
Other reconciling items (1) | Other | Other
Disaggregation of Revenue [Line Items]
Operating revenues	(20,315)	(34,857)
Other reconciling items (3)
Disaggregation of Revenue [Line Items]
Operating revenues	$ 20,315	$ 34,857