Revenue (Summary of Revenue by Category) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Product Information [Line Items]
Total revenue	$ 24,621	$ 21,578	$ 41,046	$ 40,940
Product [Member]
Product Information [Line Items]
Total revenue	21,250	18,485	34,707	34,767
Instrument [Member]
Product Information [Line Items]
Total revenue	12,664	8,525	18,287	15,669
Consumable [Member]
Product Information [Line Items]
Total revenue	8,586	9,960	16,420	19,098
Service and Other [Member]
Product Information [Line Items]
Total revenue	$ 3,371	$ 3,093	$ 6,339	$ 6,173

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration