Condensed Consolidated Income Statements - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Condensed Consolidated Income Statements [Abstract]
Revenues (note 6)	$ 128,876	$ 109,318	$ 419,626	$ 380,413
Costs of services, excluding depreciation and amortization (note 7)	14,750	12,045	49,821	40,681
Gross revenue, net of expenses	114,126	97,273	369,805	339,732
Selling, general and administrative expenses (note 7)	69,000	58,170	211,153	187,165
Acquisition-related costs (note 7)	4,691		5,440
Depreciation and amortization expenses (note 7)	10,196	10,017	30,560	31,402
Gain on disposition of property, plant and equipment	(570)	(234)	(1,017)	(1,200)
Impairment loss (note 8)	28,243		28,243
Foreign exchange loss (gain)	281	718	332	(2,051)
Operating income	2,285	28,602	95,094	124,416
Interest income	369	548	1,354	2,075
Interest expense	(934)	(1,239)	(3,357)	(3,816)
Equity income (note 19)	213	363	1,209	769
Other, net	247	739	1,214	2,370
Other income (expense)	(105)	411	420	1,398
Income before income taxes	2,180	29,013	95,514	125,814
Income tax expense (recovery) (note 9):
Current	9,652	8,700	35,767	38,778
Deferred	(2,472)	(934)	(5,838)	(4,167)
Income tax expense	7,180	7,766	29,929	34,611
Net income (loss)	(5,000)	21,247	65,585	91,203
Net income (loss) attributable to:
Stockholders	(5,137)	20,825	63,979	89,685
Non-controlling interests	$ 137	$ 422	$ 1,606	$ 1,518
Earnings (loss) per share attributable to stockholders (note 11):
Basic	$ (0.05)	$ 0.19	$ 0.60	$ 0.84
Diluted	$ (0.05)	$ 0.19	$ 0.60	$ 0.83
Weighted average number of shares outstanding (note 11):
Basic	106,622,376	107,137,417	106,595,088	107,041,819
Diluted	107,525,051	107,517,888	107,221,390	107,433,359