Estimated Useful Life of Assets (Detail)	12 Months Ended
	Dec. 31, 2012
Machinery and equipment - manufacturing and drilling
Property, Plant and Equipment [Line Items]
Property and equipment, estimated maximum useful life	10 years
Minimum | Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, estimated maximum useful life	15 years
Minimum | Machinery and equipment - computers
Property, Plant and Equipment [Line Items]
Property and equipment, estimated maximum useful life	3 years
Minimum | Office equipment - furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, estimated maximum useful life	5 years
Minimum | Office equipment - other
Property, Plant and Equipment [Line Items]
Property and equipment, estimated maximum useful life	5 years
Minimum | Automobiles
Property, Plant and Equipment [Line Items]
Property and equipment, estimated maximum useful life	5 years
Maximum | Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, estimated maximum useful life	20 years
Maximum | Machinery and equipment - computers
Property, Plant and Equipment [Line Items]
Property and equipment, estimated maximum useful life	5 years
Maximum | Office equipment - furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, estimated maximum useful life	15 years
Maximum | Office equipment - other
Property, Plant and Equipment [Line Items]
Property and equipment, estimated maximum useful life	10 years
Maximum | Automobiles
Property, Plant and Equipment [Line Items]
Property and equipment, estimated maximum useful life	7 years