CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net income	$ 5,406	$ 4,523
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property and equipment	3,439	3,223
Amortization of intangible assets	367	350
Accretion of closure and post-closure obligations	307	335
Unrealized foreign currency (gain) loss	1,057	(1,201)
Deferred income taxes	(716)	338
Share-based compensation expense	146	203
Unrecognized tax benefits	3	3
Net (gain) loss on sale of property and equipment	(41)	22
Changes in assets and liabilities:
Receivables	1,473	7,624
Income tax receivable		42
Other assets	732	(66)
Accounts payable and accrued liabilities	(556)	(967)
Deferred revenue	1,269	(295)
Accrued salaries and benefits	(3,106)	(1,526)
Income tax payable	3,528	896
Closure and post-closure obligations	(1,043)	(82)
Net cash provided by operating activities	12,265	13,422
Cash flows from investing activities:
Purchases of property and equipment	(6,752)	(2,386)
Proceeds from sale of property and equipment	52	66
Net cash used in investing activities	(6,700)	(2,320)
Cash flows from financing activities:
Payments on reducing revolving line of credit	(4,000)	(8,500)
Proceeds from exercise of stock options	1,050	44
Deferred financing costs paid	(177)
Proceeds from reducing revolving line of credit		3,000
Dividends paid		(3,282)
Other	2	(287)
Net cash used in financing activities	(3,125)	(9,025)
Effect of foreign exchange rate changes on cash	(49)	32
Increase in cash and cash equivalents	2,391	2,109
Cash and cash equivalents at beginning of period	2,120	4,289
Cash and cash equivalents at end of period	4,511	6,398
Supplemental Disclosures
Income taxes paid, net of receipts	378	1,612
Interest paid	184	236
Non-cash investing and financing activities:
Capital expenditures in accounts payable	1,645	916
Restricted stock issued from treasury shares	$ 629	$ 247