Drilling and Other Property and Equipment - Additional Information (Detail) (USD $)	Dec. 31, 2012 Drillship	Dec. 31, 2011 Drillship
Property, Plant and Equipment [Line Items]
Construction work-in-progress	$ 990,964,000	$ 504,805,000
Number of drillships under construction	4	3
Jack-Up Rigs [Member]
Property, Plant and Equipment [Line Items]
Pre-tax gain on sale of rigs	76,500,000
Number of rigs sold during period	6
Net book value of assets retired	55,400,000
Drilling Rigs [Member]
Property, Plant and Equipment [Line Items]
Transferred aggregate net book value of rig	73,200,000
Number of rigs transferred at net book value to Asset held for sale	4
Ocean Onyx [Member]
Property, Plant and Equipment [Line Items]
Construction work-in-progress	167,400,000	14,600,000
Drillship [Member]
Property, Plant and Equipment [Line Items]
Construction work-in-progress	741,100,000	490,200,000
Ocean Apex [Member]
Property, Plant and Equipment [Line Items]
Construction work-in-progress	$ 82,500,000