Income Taxes - Income Tax Years Subject to Examination by Major Tax Jurisdictions (Detail)	12 Months Ended
	Dec. 31, 2013
United States
Income Tax years subject to examination by major tax jurisdictions
Income tax examination year under examination range start
Income tax examination year under examination range end
Gabon
Income Tax years subject to examination by major tax jurisdictions
Income tax examination year under examination range start
Income tax examination year under examination range end