General Information - Summary of Cold Stacked Rigs Evaluated for Impairment (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011 Rigs	Dec. 31, 2010 Rigs
Property, Plant and Equipment [Line Items]
Total number of cold stacked rigs	8	7
Aggregate net book value	$ 76.5	$ 78.0
Mid-Water Floaters [Member]
Property, Plant and Equipment [Line Items]
Total number of cold stacked rigs	3	3
Jack-Up Rigs [Member]
Property, Plant and Equipment [Line Items]
Total number of cold stacked rigs	5	4