Organization and Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017 USD ($) Segment subsidiary Source	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)
Summary Of Significant Accounting Policy [Line Items]
Number of wholly owned subsidiaries | subsidiary	2
Number of reportable segments | Segment	2
Number of revenue sources | Source	2
Warranty period	1 year
Corporate owned life insurance policies fair value	$ 3,518		$ 3,240
Net income	$ 4,580	$ 3,463
Additional Paid-in Capital | Accounting Standards Update 2016-09
Summary Of Significant Accounting Policy [Line Items]
Cumulative effect of new accounting principle in period of adoption - APIC			500
Retained Earnings | Accounting Standards Update 2016-09
Summary Of Significant Accounting Policy [Line Items]
Cumulative effect of new accounting principle in period of adoption - APIC			$ (500)
Minimum
Summary Of Significant Accounting Policy [Line Items]
Service term for services purchased	3 years
Maximum
Summary Of Significant Accounting Policy [Line Items]
Service term for services purchased	5 years
Extended Product Warranty | Minimum
Summary Of Significant Accounting Policy [Line Items]
Extended warranty period	1 year
Service term for services purchased	1 year
Extended Product Warranty | Maximum
Summary Of Significant Accounting Policy [Line Items]
Extended warranty period	5 years
Service term for services purchased	5 years
Evidence. Com
Summary Of Significant Accounting Policy [Line Items]
Subscription period	5 years
Device upgrade period	2 years 6 months
Customer Concentration Risk | Sales Revenue, Net | One customer
Summary Of Significant Accounting Policy [Line Items]
Concentration risk, percentage		10.90%
Customer Concentration Risk | Accounts Receivable | One customer
Summary Of Significant Accounting Policy [Line Items]
Concentration risk, percentage			14.50%