Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating activities:
Net income	$ 18,172	$ 17,207
Adjustments for items not affecting cash:
Depreciation and amortization expenses	17,115	16,191
Stock option compensation expense	1,539	2,343
Equity-classified PSU expense	2,368	3,035
Deferred income tax expense	1,057	1,265
Unrealized foreign exchange (gain) loss	(48)	263
Gain on disposition of property, plant and equipment	(149)	(345)
Amortization of debt issuance costs	934	1,066
Other, net	3,510	948
Net changes in operating assets and liabilities	27,405	25,265
Net cash provided by operating activities	71,903	67,238
Investing activities:
Property, plant and equipment additions	(2,801)	(2,564)
Intangible asset additions	(5,625)	(7,034)
Proceeds on disposition of property, plant and equipment	262	1,066
Other, net		(4,674)
Net cash used in investing activities	(8,164)	(13,206)
Financing activities:
Dividends paid to stockholders	(19,568)	(18,245)
Issuances of share capital	1,628	4,313
Payment of withholding taxes on issuance of shares	(2,047)
Proceeds from short-term debt	6,741	308
Repayment of short-term debt	(17,946)	(1,754)
Repayment of long-term debt	(12,235)	(29,237)
Repayment of finance lease obligations	(1,269)	(802)
Net cash used in financing activities	(44,696)	(45,417)
Effect of changes in foreign currency rates on cash, cash equivalents, and restricted cash	(1,376)	1,627
Increase	17,667	10,242
Beginning of period	305,567	331,116
Cash, cash equivalents, and restricted cash, end of period	$ 323,234	$ 341,358