Impact of Recently Issued Accounting Pronouncements - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Recognized service revenue	$ 7,200	$ 16,200
Retained earnings	172,649	172,649		$ 168,624
Deferred cost asset	2,500	2,500
Allowance for sales returns (less than)	100	100
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings			$ 2,400
Deferred cost asset			$ 2,400
Prepaid expenses and other current assets
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred cost asset	1,800	1,800
Other long-term assets
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred cost asset	$ 700	$ 700
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Extended product warranty term		1 month
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Extended product warranty term		3 years