Condensed Consolidated Income Statements - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues:
Total revenue	$ 273,255	$ 303,429
Operating expenses:
Selling, general and administrative expenses	98,385	95,184
Acquisition-related costs		669
Depreciation and amortization expenses	19,293	17,115
Gain on disposition of property, plant and equipment	(47)	(149)
Foreign exchange loss	602	478
Total operating expenses	239,173	269,841
Operating income	34,082	33,588
Interest expense	(9,182)	(10,816)
Other income, net	3,577	2,039
Income before income taxes	28,477	24,811
Income tax expense	5,648	6,639
Net income	22,829	18,172
Net income attributable to:
Stockholders	22,809	18,164
Non-controlling interests	20	8
Net income	$ 22,829	$ 18,172
Earnings per share attributable to stockholders:
Basic	$ 0.21	$ 0.17
Diluted	$ 0.21	$ 0.17
Weighted average number of shares outstanding:
Basic	109,248,880	108,765,489
Diluted	110,482,837	110,044,213
Service Revenue [Member]
Revenues:
Total revenue	$ 183,123	$ 172,372
Operating expenses:
Direct expenses	39,355	36,069
Inventory Sales Revenue [Member]
Revenues:
Total revenue	90,132	131,057
Operating expenses:
Direct expenses	$ 81,585	$ 120,475