Income Taxes - Major Jurisdictions no Longer Subject to Income Tax Examinations by Tax Authorities (Detail)	12 Months Ended
	Dec. 31, 2017
U.S. federal
Income Tax Examination [Line Items]
Years No Longer Subject to Audit	2010 and prior
California (U.S.)
Income Tax Examination [Line Items]
Years No Longer Subject to Audit	2008 and prior
Canada
Income Tax Examination [Line Items]
Years No Longer Subject to Audit	2009 and prior
Japan
Income Tax Examination [Line Items]
Years No Longer Subject to Audit	2010 and prior
South Korea
Income Tax Examination [Line Items]
Years No Longer Subject to Audit	2011 and prior
United Kingdom
Income Tax Examination [Line Items]
Years No Longer Subject to Audit	2013 and prior