Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Activities
Net income	$ 73,486	$ 44,315	$ 40,045
Adjustments to reconcile net income to cash provided by operating activities:
Provision for doubtful accounts	71	187	482
Depreciation - PP&E	12,884	11,616	11,267
Depreciation - Rental	6,725	5,531	6,429
Amortization of intangibles	3,505	3,317	3,104
Amortization of debt issuance	221	203	213
Stock-based compensation expense	2,450	1,869	1,414
Provision for deferred income tax expense	2,052	1,328	2,620
Gain on sale of property, plant and equipment	(361)	(341)	(345)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	(27,029)	(23,134)	3,876
Inventories	(25,991)	142	12,340
Rental equipment	(22,424)	(3,054)	315
Prepaid expenses and other	(583)	2,845	(5,634)
Trade accounts payable and accrued liabilities	4,130	11,688	(5,382)
Income taxes payable	(10,332)	2,357	2,908
Long term tax payable	(6,196)	12,478	0
Other assets and liabilities, net	302	(543)	2,132
Net cash provided by operating activities	12,910	70,804	75,784
Investing Activities
Acquisitions, net of cash acquired	0	(38,553)	(188)
Purchase of property, plant and equipment	(26,587)	(13,490)	(9,711)
Proceeds from sale of property, plant and equipment	1,341	767	1,293
Purchase of patents	(112)	0	(50)
Net cash used in investing activities	(25,358)	(51,276)	(8,656)
Financing Activities
Borrowings on bank revolving credit facility	159,000	143,000	79,000
Repayment on bank revolving credit facility	(134,000)	(153,000)	(153,000)
Principal payments on long-term debt and capital leases	216	(17)	(38)
Proceeds from issuance of long-term debt	0	0	48
Debt issuance cost	0	0	(593)
Dividends paid	(5,124)	(4,614)	(4,114)
Proceeds from exercise of stock options	2,552	2,397	1,369
Common stock repurchased	(436)	(166)	(19)
Net cash used in financing activities	22,208	(12,400)	(77,347)
Effect of exchange rate changes on cash	(1,090)	1,452	90
Net change in cash and cash equivalents	8,670	8,580	(10,129)
Cash and cash equivalents at beginning of the year	25,373	16,793	26,922
Cash and cash equivalents at end of the year	34,043	25,373	16,793
Cash paid during the year for:
Interest	5,199	5,217	5,796
Income taxes	$ 30,295	$ 23,175	$ 16,637