Condensed Consolidated Income Statements - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Condensed Consolidated Income Statements [Abstract]
Revenues (note 6)	$ 124,499	$ 131,945
Costs of services, excluding depreciation and amortization (note 7)	12,813	15,313
Gross revenue, net of expenses	111,686	116,632
Selling, general and administrative expenses (note 7)	70,575	67,110
Acquisition-related costs (note 7)	8,627	1,197
Depreciation and amortization expenses (note 7)	10,338	10,080
Gain on disposition of property, plant and equipment	(721)	(246)
Foreign exchange gain	(730)	(683)
Operating income	23,597	39,174
Other income (expense):
Interest income	955	498
Interest expense	(8,133)	(1,363)
Equity income (loss) (note 17)	(53)	519
Other, net	1,382	698
Other income (expense)	(5,849)	352
Income before income taxes	17,748	39,526
Income tax expense (recovery) (note 8):
Current	7,488	10,009
Deferred	(173)	(477)
Income tax expense	7,315	9,532
Net income	10,433	29,994
Net income attributable to:
Stockholders	10,377	29,406
Non-controlling interests	$ 56	$ 588
Earnings per share attributable to stockholders (note 9):
Basic	$ 0.10	$ 0.28
Diluted	$ 0.10	$ 0.27
Weighted average number of shares outstanding (note 9):
Basic	106,851,595	106,917,280
Diluted	107,788,949	107,159,010