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, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment	$ 8,421,709	$ 9,087,942
Less: accumulated depreciation	(2,989,020)	(3,361,007)
Drilling and other property and equipment, net	5,432,689	5,726,935
Drilling Rigs and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	8,279,491	8,950,385
Land and Buildings [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	63,309	64,449
Office Equipment and Other [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 78,909	$ 73,108