Property and Equipment - Property and Equipment, at Cost (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	$ 14,442,922	$ 19,198,767
Drilling Equipment and Facilities [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	13,254,240	17,130,986
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	969,985	1,854,434
Other [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	$ 218,697	$ 213,347