Drilling and Other Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Apr. 30, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Property Plant And Equipment [Line Items]
Gain (loss) on disposition of assets		$ 9,436	$ 50	$ 5,149	$ 560
Semisubmersible Rig [Member]
Property Plant And Equipment [Line Items]
Gain (loss) on disposition of assets	$ 14,300
Other Property and Equipment [Member]
Property Plant And Equipment [Line Items]
Gain (loss) on disposition of assets				$ (9,200)