Organization and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total revenues	$ 204,267,000	$ 186,748,000	$ 575,559,000	$ 516,343,000
Deferred revenues	98,411,000		98,411,000		$ 89,397,000
Short-term deferred revenues	87,777,000		87,777,000		$ 78,774,000
Revenues from sales-type leases	11,400,000	5,900,000	28,800,000	19,300,000
Fees to GPOs	2,200,000	2,100,000	6,200,000	5,400,000
Deferred revenues recognized	10,900,000		78,900,000
Capitalized commissions	5,300,000	4,600,000	16,200,000	13,300,000
Impairment loss	0		0
Product revenues
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total revenues	149,709,000	136,838,000	$ 415,004,000	365,834,000
Difference between Revenue Guidance in Effect before and after Topic 606 | Product revenues
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total revenues	$ 600,000	$ 200,000		$ 500,000
Lease Receivable | Customer Concentration Risk
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Concentration risk percentage			44.00%