Components of Income (Loss) from Continuing Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income (loss) from continuing operations before income taxes:
Income from continuing operations before income taxes	$ 76,134	$ 32,522	$ 46,022
CANADA
Income (loss) from continuing operations before income taxes:
Foreign	(2,036)	(1,872)	(1,674)
UNITED STATES
Income (loss) from continuing operations before income taxes:
U.S.	37,327	20,422	23,298
Other Countries
Income (loss) from continuing operations before income taxes:
Foreign	$ 40,843	$ 13,972	$ 24,398