Summary of Significant Accounting Policies (Details 2)	12 Months Ended
	Dec. 31, 2012
Drilling rigs excluding jackup rigs
Property, Plant and Equipment
Operating rig asset depreciable life, operating days	4900 days
Non-operating rig asset depreciable life	20 years
Jackup rigs
Property, Plant and Equipment
Operating rig asset depreciable life, operating days	8030 days
Non-operating rig asset depreciable life	30 years
Buildings | Minimum
Property, Plant and Equipment
Estimated useful life	10 years
Buildings | Maximum
Property, Plant and Equipment
Estimated useful life	30 years
Well-servicing rigs | Minimum
Property, Plant and Equipment
Estimated useful life	3 years
Well-servicing rigs | Maximum
Property, Plant and Equipment
Estimated useful life	15 years
Marine transportation and supply vessels | Minimum
Property, Plant and Equipment
Estimated useful life	10 years
Marine transportation and supply vessels | Maximum
Property, Plant and Equipment
Estimated useful life	25 years
Oilfield hauling and mobile equipment and other machinery and equipment | Minimum
Property, Plant and Equipment
Estimated useful life	3 years
Oilfield hauling and mobile equipment and other machinery and equipment | Maximum
Property, Plant and Equipment
Estimated useful life	10 years