CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income	$ 9,243	$ 5,185
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property and equipment	6,605	6,633
Amortization of intangible assets	2,302	2,670
Accretion of closure and post-closure obligations	1,074	1,073
Unrealized foreign currency loss (gain)	654	(168)
Deferred income taxes	450	179
Share-based compensation expense	1,068	918
Net loss on disposition of assets	17	219
Amortization and write-off of debt issuance costs	202	504
Amortization and write-off of debt discount		37
Changes in assets and liabilities (net of effects of business acquisitions and divestitures):
Receivables	14,947	2,991
Income taxes receivable	(573)	2,045
Other assets	(792)	(417)
Accounts payable and accrued liabilities	(4,163)	(2,577)
Deferred revenue	301	2,037
Accrued salaries and benefits	(2,432)	(124)
Income taxes payable	215	(61)
Closure and post-closure obligations	(288)	(271)
Net cash provided by operating activities	28,830	20,873
Cash flows from investing activities:
Purchases of property and equipment	(7,558)	(7,151)
Proceeds from sale of property and equipment	42	40
Purchases of restricted investments	(498)	(2)
Proceeds from sale of restricted investments	417
Net cash used in investing activities	(7,597)	(7,113)
Cash flows from financing activities:
Payments on long-term debt		(4,726)
Payment on short-term borrowings		(13,438)
Proceeds from short-term borrowings		11,260
Dividends paid	(3,937)	(3,923)
Proceeds from exercise of stock options	731	496
Payment of equipment financing obligations	(108)	(85)
Other	(313)	(74)
Net cash used in financing activities	(3,627)	(10,490)
Effect of foreign exchange rate changes on cash	(488)	29
Increase in Cash and cash equivalents and Restricted cash	17,118	3,299
Cash and cash equivalents and Restricted cash at beginning of period	28,799	8,722
Cash and cash equivalents and Restricted cash at end of period	45,917	12,021
Supplemental Disclosures
Income taxes paid, net of receipts	3,429	886
Interest paid	2,554	3,618
Non-cash investing and financing activities:
Capital expenditures in accounts payable	245	$ 1,766
Restricted stock issued from treasury shares	$ 11