Income taxes - Income Tax Expense (Recovery) Summary (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Effective statutory federal, state and provincial income tax rate	26.50%	26.50%	28.25%
Effective tax expense (recovery) on income (loss) from continuing operations before income taxes	$ (1,235)	$ 271	$ (42)
Increase (decrease) results from:
Non-deductible share-based compensation expense	69	114	141
Income taxed at different rates in foreign jurisdictions	33	38	(1,395)
Tax benefit on capital loss	(461)
Income from discontinued operations	84	762	2,345
Other	(123)	55	119
Income tax expense (recovery) from continuing operations	$ (1,633)	$ 1,240	$ 1,168