Drilling and Other Property and Equipment - Summary of Cost and Accumulated Depreciation of Drilling and Other Property and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Property and equipment	$ 8,979,647	$ 8,222,778
Less: accumulated depreciation	(3,648,177)	(3,357,806)
Drilling and other property and equipment, net	5,331,470	4,864,972
Drilling rigs and equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	7,295,964	7,107,279
Construction work-in-progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	1,553,430	990,964
Land and buildings [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	65,362	64,296
Office equipment and other [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 64,891	$ 60,239