Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Operating revenues	$ 782,080	$ 779,425	$ 761,920	$ 734,194	$ 708,277	$ 662,103	$ 631,355	$ 562,550	$ 3,057,619	$ 2,564,285	$ 2,227,839
U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									1,347,448	973,464	642,835
Saudi Arabia
Disaggregation of Revenue [Line Items]
Operating revenues									764,500	727,700	731,400
Operating segment | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues									1,272,588	1,011,852	585,063
Operating segment | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									136,722	77,015	79,982
Operating segment | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues									53,909	52,108	75,518
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									140,531	96,601	65,012
Operating segment | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									950,222	896,065	908,525
Operating segment | Latin America [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									384,249	391,893	307,199
Operating segment | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									240,274	211,921	308,845
Operating segment | U.S. Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									1,083,227	805,223	554,072
Operating segment | U.S. Drilling | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues									910,819	681,669	402,415
Operating segment | U.S. Drilling | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									122,946	75,994	79,730
Operating segment | U.S. Drilling | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues									49,462	47,560	71,927
Operating segment | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									105,000	82,929	51,472
Operating segment | Canada Drilling | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									105,000	82,929	51,472
Operating segment | International Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									1,469,038	1,474,060	1,508,890
Operating segment | International Drilling | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									888,500	875,175	894,216
Operating segment | International Drilling | Latin America [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									360,385	388,235	306,042
Operating segment | International Drilling | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									220,153	210,650	308,632
Operating segment | Drilling Solutions
Disaggregation of Revenue [Line Items]
Operating revenues									250,242	140,701	63,759
Operating segment | Drilling Solutions | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues									173,219	118,574	49,377
Operating segment | Drilling Solutions | Offshore Gulf Of Mexico [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									13,776	1,021	252
Operating segment | Drilling Solutions | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues									3,670	3,925	3,036
Operating segment | Drilling Solutions | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									5,849	6,054	4,572
Operating segment | Drilling Solutions | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									35,486	7,397	5,152
Operating segment | Drilling Solutions | Latin America [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									15,350	3,266	1,157
Operating segment | Drilling Solutions | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									2,892	464	213
Operating segment | Rig Technologies
Disaggregation of Revenue [Line Items]
Operating revenues									270,988	234,542	151,951
Operating segment | Rig Technologies | Lower 48
Disaggregation of Revenue [Line Items]
Operating revenues									188,550	211,609	133,271
Operating segment | Rig Technologies | ALASKA
Disaggregation of Revenue [Line Items]
Operating revenues									777	623	555
Operating segment | Rig Technologies | Canada Drilling
Disaggregation of Revenue [Line Items]
Operating revenues									29,682	7,618	8,968
Operating segment | Rig Technologies | Middle East And Asia [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									26,236	13,493	9,157
Operating segment | Rig Technologies | Latin America [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									8,514	392
Operating segment | Rig Technologies | Europe Africa And CIS [Member]
Disaggregation of Revenue [Line Items]
Operating revenues									17,229	807
Other reconciling items (1)
Disaggregation of Revenue [Line Items]
Operating revenues									(120,876)	(173,170)	(102,305)
Other reconciling items (1) | Other
Disaggregation of Revenue [Line Items]
Operating revenues									(120,876)	(173,170)	(102,305)
Other reconciling items (1) | Other
Disaggregation of Revenue [Line Items]
Operating revenues									(120,876)	(173,170)	(102,305)
Other reconciling items (1) | Other | Other
Disaggregation of Revenue [Line Items]
Operating revenues									$ (120,876)	$ (173,170)	$ (102,305)