Components of Income Tax Provision (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Components Of Income Tax Expense Benefit [Line Items]
Current income tax provision (benefit)	$ 12,285	$ 12,086	$ 5,730
Deferred income tax provision (benefit)	(1,766)	(1,692)	(6,736)
Income Tax Provision (benefit)	10,519	10,394	(1,006)
CANADA
Components Of Income Tax Expense Benefit [Line Items]
Current income tax provision (benefit)	43	96	175
Deferred income tax provision (benefit)	0	0	0
UNITED STATES
Components Of Income Tax Expense Benefit [Line Items]
Current income tax provision (benefit)	9,678	8,136	3,615
Deferred income tax provision (benefit)	(2,378)	(3,239)	(6,731)
Other Countries
Components Of Income Tax Expense Benefit [Line Items]
Current income tax provision (benefit)	2,564	3,854	1,940
Deferred income tax provision (benefit)	$ 612	$ 1,547	$ (5)