Impairments and Other Charges (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($) item	Dec. 31, 2017 USD ($)
Tangible Assets And Equipment
Provision for retirement of assets			$ 33,205	$ 14,617
Impairment of long-lived assets			10,363	45,570	$ 6,895
Subtotal			43,568	60,187	6,895
Goodwill And Intangible Assets:
Goodwill impairments			155,973
Intangible asset impairment			47,731
Subtotal			203,704
Other Charges:
Provision for international activities			43,220	64,700
Severance and transaction related costs			11,447	14,323	21,628
Loss (gain) on debt buyback			(11,468)	5,268	16,013
Divestiture of International assets				64,668
Total impairments and other charges			290,471	144,446	44,536
Transaction related costs				14,300	21,600
Principal amount redeemed			468,300
Payment of long-term debt			455,360	$ 878,278	381,814
Number of remaining SCR rigs retired | item				13
U.S. Drilling
Goodwill And Intangible Assets:
Goodwill impairments	$ 52,200
Canada Drilling
Tangible Assets And Equipment
Provision for retirement of assets			17,800
International Drilling
Tangible Assets And Equipment
Provision for retirement of assets			15,400
Impairment of long-lived assets			2,500
Goodwill And Intangible Assets:
Goodwill impairments		$ 75,600
Other Charges:
Number of offshore drilling rigs sold | item				3
Number of workers rigs sold | item				8
Rig Technologies
Goodwill And Intangible Assets:
Goodwill impairments	10,100	$ 18,000
Senior Notes.
Other Charges:
Loss (gain) on debt buyback					16,000
Principal amount redeemed				$ 873,000	367,900
Debt Instrument, Repurchased Face Amount	$ 468,300		468,300	873,000	367,900
Payment of long-term debt			$ 461,100	$ 906,500	$ 381,700