Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Operating revenues	$ 714,261	$ 758,076	$ 771,406	$ 799,640	$ 782,080	$ 779,425	$ 761,920	$ 734,194	$ 3,043,383	$ 3,057,619	$ 2,564,285
U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									1,554,442	1,347,448	973,464
Saudi Arabia
Disaggregation of Revenue [Line Items]
Operating revenues									696,400	764,500	727,700
Operating segment | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues									1,365,077	1,272,588	1,011,852
Operating segment | Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues									170,262	136,722	77,015
Operating segment | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues									67,899	53,909	52,108
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									78,875	140,531	96,601
Operating segment | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									865,889	950,222	896,065
Operating segment | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues									373,065	384,249	391,893
Operating segment | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									225,301	240,274	211,921
Operating segment | U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									1,240,936	1,083,227	805,223
Operating segment | U.S. Drilling | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues									1,021,879	910,819	681,669
Operating segment | U.S. Drilling | Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues									156,931	122,946	75,994
Operating segment | U.S. Drilling | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues									62,126	49,462	47,560
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									68,274	105,000	82,929
Operating segment | Canada Drilling | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									68,274	105,000	82,929
Operating segment | International Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									1,324,142	1,469,038	1,474,060
Operating segment | International Drilling | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									765,493	888,500	875,175
Operating segment | International Drilling | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues									355,189	360,385	388,235
Operating segment | International Drilling | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									203,460	220,153	210,650
Operating segment | Drilling Solutions
Disaggregation of Revenue [Line Items]
Operating revenues									252,790	250,242	140,701
Operating segment | Drilling Solutions | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues									170,639	173,219	118,574
Operating segment | Drilling Solutions | Offshore Gulf Of Mexico
Disaggregation of Revenue [Line Items]
Operating revenues									13,331	13,776	1,021
Operating segment | Drilling Solutions | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues									4,787	3,670	3,925
Operating segment | Drilling Solutions | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									1,749	5,849	6,054
Operating segment | Drilling Solutions | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									43,941	35,486	7,397
Operating segment | Drilling Solutions | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues									15,558	15,350	3,266
Operating segment | Drilling Solutions | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									2,785	2,892	464
Operating segment | Rig Technologies
Disaggregation of Revenue [Line Items]
Operating revenues									260,226	270,988	234,542
Operating segment | Rig Technologies | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues									172,559	188,550	211,609
Operating segment | Rig Technologies | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues									986	777	623
Operating segment | Rig Technologies | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									8,852	29,682	7,618
Operating segment | Rig Technologies | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									56,455	26,236	13,493
Operating segment | Rig Technologies | Latin America
Disaggregation of Revenue [Line Items]
Operating revenues									2,318	8,514	392
Operating segment | Rig Technologies | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									19,056	17,229	807
Other reconciling items (1)
Disaggregation of Revenue [Line Items]
Operating revenues									(102,985)	(120,876)	(173,170)
Other reconciling items (1) | Other
Disaggregation of Revenue [Line Items]
Operating revenues									(102,985)	(120,876)	(173,170)
Other reconciling items (1) | Other
Disaggregation of Revenue [Line Items]
Operating revenues									(102,985)	(120,876)	(173,170)
Other reconciling items (1) | Other | Other
Disaggregation of Revenue [Line Items]
Operating revenues									$ (102,985)	$ (120,876)	$ (173,170)