Annual report pursuant to Section 13 and 15(d)

Income Taxes - Open Tax Years by Major Tax Jurisdiction (Detail)

v2.4.1.9
Income Taxes - Open Tax Years by Major Tax Jurisdiction (Detail)
 12 Months Ended
Dec. 31, 2014
Colombia [Member]  
Open Tax Years By Major Jurisdiction [Line Items]  
Open Tax Years by Major Tax Jurisdiction 2010-present
KAZAKHSTAN  
Open Tax Years By Major Jurisdiction [Line Items]  
Open Tax Years by Major Tax Jurisdiction 2007-present
MEXICO  
Open Tax Years By Major Jurisdiction [Line Items]  
Open Tax Years by Major Tax Jurisdiction 2009-present
Papua New Guinea [Member]  
Open Tax Years By Major Jurisdiction [Line Items]  
Open Tax Years by Major Tax Jurisdiction 2011-present
Russia [Member]  
Open Tax Years By Major Jurisdiction [Line Items]  
Open Tax Years by Major Tax Jurisdiction 2011-present
United States - Federal [Member]  
Open Tax Years By Major Jurisdiction [Line Items]  
Open Tax Years by Major Tax Jurisdiction 2012-present
United Kingdom [Member]  
Open Tax Years By Major Jurisdiction [Line Items]  
Open Tax Years by Major Tax Jurisdiction 2012-present