Drilling and Other Property and Equipment - Summary of Cost and Accumulated Depreciation of Drilling and Other Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Property and equipment	$ 8,067,434	$ 8,366,400
Less accumulated depreciation	(2,916,558)	(3,182,178)
Drilling and other property and equipment, net	5,150,876	5,184,222
Drilling Rigs and Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment	7,911,380	8,210,824
Land and Buildings [Member]
Property Plant And Equipment [Line Items]
Property and equipment	64,102	63,757
Office Equipment and Other [Member]
Property Plant And Equipment [Line Items]
Property and equipment	$ 91,952	$ 91,819