Income Taxes - Tax Years Subject to Examination by Tax Authorities (Detail)	12 Months Ended
	Dec. 31, 2014
Brazil
Disclosure Income Tax Components Of Consolidated Income Taxes Detail [Line Items]
Income tax examination, year(s) under examination	2009 - 2014
Canada
Disclosure Income Tax Components Of Consolidated Income Taxes Detail [Line Items]
Income tax examination, year(s) under examination	2007 - 2014
Ecuador
Disclosure Income Tax Components Of Consolidated Income Taxes Detail [Line Items]
Income tax examination, year(s) under examination	2001 - 2014
Mexico
Disclosure Income Tax Components Of Consolidated Income Taxes Detail [Line Items]
Income tax examination, year(s) under examination	2007 - 2014
Norway
Disclosure Income Tax Components Of Consolidated Income Taxes Detail [Line Items]
Income tax examination, year(s) under examination	2013 - 2014
Russia
Disclosure Income Tax Components Of Consolidated Income Taxes Detail [Line Items]
Income tax examination, year(s) under examination	2011 - 2014
Saudi Arabia
Disclosure Income Tax Components Of Consolidated Income Taxes Detail [Line Items]
Income tax examination, year(s) under examination	2001 - 2014
United Kingdom
Disclosure Income Tax Components Of Consolidated Income Taxes Detail [Line Items]
Income tax examination, year(s) under examination	2009 - 2014
United States
Disclosure Income Tax Components Of Consolidated Income Taxes Detail [Line Items]
Income tax examination, year(s) under examination	2011 - 2014