Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Operating revenues	$ 443,396	$ 438,352	$ 533,931	$ 718,364	$ 714,261	$ 758,076	$ 771,406	$ 799,640	$ 2,134,043	$ 3,043,383	$ 3,057,619
United States
Disaggregation of Revenue [Line Items]
Operating revenues									841,531	1,554,442	1,347,448
Saudi Arabia
Disaggregation of Revenue [Line Items]
Operating revenues									642,700	696,400	764,500
Operating segment | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues									691,963	1,365,077	1,272,588
Operating segment | U.S. Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues									135,601	170,262	136,722
Operating segment | Alaska
Disaggregation of Revenue [Line Items]
Operating revenues									39,221	67,899	53,909
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									59,461	78,875	140,531
Operating segment | Middle East & Asia
Disaggregation of Revenue [Line Items]
Operating revenues									827,501	865,889	950,222
Operating segment | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues									235,685	373,065	384,249
Operating segment | Europe, Africa & CIS
Disaggregation of Revenue [Line Items]
Operating revenues									191,440	225,301	240,274
Operating segment | U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									713,057	1,240,936	1,083,227
Operating segment | U.S. Drilling | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues									548,859	1,021,879	910,819
Operating segment | U.S. Drilling | U.S. Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues									126,292	156,931	122,946
Operating segment | U.S. Drilling | Alaska
Disaggregation of Revenue [Line Items]
Operating revenues									37,906	62,126	49,462
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									54,753	68,274	105,000
Operating segment | Canada Drilling | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									54,753	68,274	105,000
Operating segment | International Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									1,131,673	1,324,142	1,469,038
Operating segment | International Drilling | Middle East & Asia
Disaggregation of Revenue [Line Items]
Operating revenues									728,983	765,493	888,500
Operating segment | International Drilling | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues									228,930	355,189	360,385
Operating segment | International Drilling | Europe, Africa & CIS
Disaggregation of Revenue [Line Items]
Operating revenues									173,760	203,460	220,153
Operating segment | Drilling Solutions
Disaggregation of Revenue [Line Items]
Operating revenues									149,834	252,790	250,242
Operating segment | Drilling Solutions | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues									88,919	170,639	173,219
Operating segment | Drilling Solutions | U.S. Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues									9,309	13,331	13,776
Operating segment | Drilling Solutions | Alaska
Disaggregation of Revenue [Line Items]
Operating revenues									1,296	4,787	3,670
Operating segment | Drilling Solutions | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									1,137	1,749	5,849
Operating segment | Drilling Solutions | Middle East & Asia
Disaggregation of Revenue [Line Items]
Operating revenues									40,255	43,941	35,486
Operating segment | Drilling Solutions | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues									6,578	15,558	15,350
Operating segment | Drilling Solutions | Europe, Africa & CIS
Disaggregation of Revenue [Line Items]
Operating revenues									2,340	2,785	2,892
Operating segment | Rig Technologies
Disaggregation of Revenue [Line Items]
Operating revenues									131,555	260,226	270,988
Operating segment | Rig Technologies | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues									54,185	172,559	188,550
Operating segment | Rig Technologies | Alaska
Disaggregation of Revenue [Line Items]
Operating revenues									19	986	777
Operating segment | Rig Technologies | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									3,571	8,852	29,682
Operating segment | Rig Technologies | Middle East & Asia
Disaggregation of Revenue [Line Items]
Operating revenues									58,263	56,455	26,236
Operating segment | Rig Technologies | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues									177	2,318	8,514
Operating segment | Rig Technologies | Europe, Africa & CIS
Disaggregation of Revenue [Line Items]
Operating revenues									15,340	19,056	17,229
Other reconciling items
Disaggregation of Revenue [Line Items]
Operating revenues									(46,829)	(102,985)	(120,876)
Other reconciling items | Other
Disaggregation of Revenue [Line Items]
Operating revenues									(46,829)	(102,985)	(120,876)
Other reconciling items | Other
Disaggregation of Revenue [Line Items]
Operating revenues									(46,829)	(102,985)	(120,876)
Other reconciling items | Other | Other
Disaggregation of Revenue [Line Items]
Operating revenues									$ (46,829)	$ (102,985)	$ (120,876)