CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 42,017	$ 27,523	$ 20,121
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	69,546	53,582	43,755
Gain on bargain purchase	0	(11,039)	0
Losses on sales and/or abandonment of property and equipment	625	427	530
Write-off of patents and intangible assets	814	988	101
Acquired in-process research and development	644	12,136	461
Amortization of deferred credits	(142)	(147)	(170)
Amortization of long-term debt issuance costs	804	685	952
Deferred income taxes	2,052	(1,304)	(962)
Excess tax benefits from stock-based compensation	0	0	(669)
Stock-based compensation expense	6,117	4,075	2,506
Changes in operating assets and liabilities, net of effects from acquisitions:
Trade receivables	(27,522)	(12,844)	(6,816)
Other receivables	(2,754)	(3,557)	1,161
Inventories	(28,172)	(17,834)	(3,656)
Prepaid expenses and other current assets	(2,000)	(1,236)	271
Prepaid income taxes	(444)	(611)	404
Income tax refund receivables	232	(588)	406
Other assets	315	(3,735)	(3,763)
Trade payables	15,726	417	(6,835)
Accrued expenses	12,706	6,461	3,242
Income taxes payable	918	21	1,451
Long-term income taxes payable	(4,454)	4,846	0
Liabilities related to unrecognized tax benefits	267	(19)	597
Deferred compensation payable	39	1,970	712
Other long-term obligations	(801)	2,510	(200)
Total adjustments	44,516	35,204	33,478
Net cash provided by operating activities	86,533	62,727	53,599
Capital expenditures for:
Property and equipment	(63,324)	(38,623)	(32,837)
Intangible assets	(3,012)	(2,577)	(2,217)
Proceeds from sale of cost method investment	0	0	1,089
Proceeds from the sale of property and equipment	55	21	19
Issuance of notes receivable	(10,750)	0	0
Cash paid in acquisitions, net of cash acquired	(301,789)	(105,582)	(125,161)
Net cash used in investing activities	(378,820)	(146,761)	(159,107)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	214,993	143,810	5,271
Offering costs	(366)	(816)	0
Proceeds from issuance of long-term debt	639,108	197,214	219,505
Payments on long-term debt	(522,608)	(243,214)	(102,098)
Excess tax benefits from stock-based compensation	0	0	669
Long-term debt issuance costs	0	(416)	(1,948)
Contingent payments related to acquisitions	(231)	(61)	(218)
Payment of taxes related to an exchange of common stock	(2,616)	0	(86)
Net cash provided by financing activities	328,280	96,517	121,095
EFFECT OF EXCHANGE RATES ON CASH	(970)	682	(593)
NET INCREASE IN CASH AND CASH EQUIVALENTS	35,023	13,165	14,994
CASH AND CASH EQUIVALENTS:
Beginning of year	32,336	19,171	4,177
End of year	67,359	32,336	19,171
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Interest (net of capitalized interest of $647, $513 and $460, respectively)	10,324	7,707	8,872
Income taxes	8,692	6,049	2,318
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Property and equipment purchases in accounts payable	4,989	1,992	2,398
Contingent receivable in exchange for sale of equity investment	0	0	711
Receivable for issuance of common stock associated with option exercises	0	137	0
Acquisition purchases in accrued expenses and other long-term obligations	72,209	10,488	0
Merit common stock surrendered (43, 0 and 14 shares, respectively) in exchange for exercise of stock options	$ 2,261	$ 0	$ 346