Revenues - Additional Information (Detail) - 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]
Accounts receivable balances	$ 339,699				$ 558,817				$ 339,699	$ 558,817
Amount amortized and recorded in drilling revenue	492,297	$ 598,452	$ 675,765	$ 704,171	795,937	$ 867,478	$ 854,418	$ 809,164	2,470,685	3,326,997	$ 2,356,684
Contract Drilling
Disaggregation Of Revenue [Line Items]
Amount amortized and recorded in drilling revenue									1,308,350	1,430,492	$ 1,040,033
ASC Topic 606 Revenue from Contracts with Customers
Disaggregation Of Revenue [Line Items]
Accounts receivable balances	336,000				554,000				336,000	554,000
ASC Topic 606 Revenue from Contracts with Customers | Accounts Payable
Disaggregation Of Revenue [Line Items]
Total contract liability	$ 2,700				$ 7,600				2,700	7,600
ASC Topic 606 Revenue from Contracts with Customers | Contract Drilling
Disaggregation Of Revenue [Line Items]
Amount amortized and recorded in drilling revenue									$ 1,000	$ 1,600
Maximum
Disaggregation Of Revenue [Line Items]
Accounts receivable payment terms									60 days
Minimum
Disaggregation Of Revenue [Line Items]
Accounts receivable payment terms									30 days