Income Taxes - Key Jurisdictions of Company's Earliest Open Tax Years (Detail)	12 Months Ended
	Dec. 31, 2016
United States [Member]
Schedule Of Income Tax [Line Items]
Open tax year by major tax jurisdiction	2012
Canada [Member]
Schedule Of Income Tax [Line Items]
Open tax year by major tax jurisdiction	2012
Egypt [Member]
Schedule Of Income Tax [Line Items]
Open tax year by major tax jurisdiction	1998
United Kingdom [Member]
Schedule Of Income Tax [Line Items]
Open tax year by major tax jurisdiction	2014