Income Taxes - Tax Years Subject to Examination by Tax Authorities (Detail)	12 Months Ended
	Dec. 31, 2020
Canada | Earliest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2013
Canada | Latest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2020
Ecuador | Earliest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2016
Ecuador | Latest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2020
Mexico | Earliest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2012
Mexico | Latest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2020
Norway | Earliest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2015
Norway | Latest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2020
Russia | Earliest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2016
Russia | Latest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2020
Saudi Arabia | Earliest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2015
Saudi Arabia | Latest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2020
United Kingdom | Earliest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2017
United Kingdom | Latest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2020
United States | Earliest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2017
United States | Latest Tax Year
Income Tax Examination [Line Items]
Income tax examination, year(s) under examination	2020