Summary of Fair Values of Assets Acquired and Liabilities Assumed at Acquisition (Detail) - USD ($) $ in Thousands		6 Months Ended
	Nov. 01, 2018	Jun. 30, 2019	Jun. 30, 2018	Jan. 02, 2019	Dec. 31, 2018	Feb. 14, 2018
Business Acquisition [Line Items]
Goodwill		$ 10,138			$ 9,286
Purchase price net of cash acquired		1,287	$ 1,384
3VR
Business Acquisition [Line Items]
Cash						$ 195
Accounts receivable						2,029
Inventory						257
Prepaid expenses and other current assets						169
Property and equipment						334
Finite-lived intangibles						6,300
Total identifiable assets acquired						9,284
Accounts payable						(1,590)
Accrued expenses and liabilities						(726)
Deferred revenue						(2,928)
Debt						(3,622)
Total liabilities assumed						(8,866)
Net identifiable assets acquired						418
Goodwill						5,456
Purchase price						5,874
3VR | Trademarks
Business Acquisition [Line Items]
Finite-lived intangibles						400
3VR | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangibles						2,900
3VR | Developed Technology
Business Acquisition [Line Items]
Finite-lived intangibles						$ 3,000
Thursby Software Systems
Business Acquisition [Line Items]
Cash	$ 3,485
Accounts receivable	526
Inventory	1,361
Prepaid expenses and other current assets	12
Finite-lived intangibles	2,400
Total identifiable assets acquired	7,784
Accounts payable	(31)
Accrued expenses and liabilities	(67)
Deferred revenue	(243)
Other current liabilities	(4,307)
Total liabilities assumed	(4,648)
Net identifiable assets acquired	3,136
Goodwill	3,490
Purchase price	6,626
Less: cash acquired	(3,485)
Purchase price net of cash acquired	3,141
Thursby Software Systems | Trademarks
Business Acquisition [Line Items]
Finite-lived intangibles	200
Thursby Software Systems | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangibles	1,500
Thursby Software Systems | Developed Technology
Business Acquisition [Line Items]
Finite-lived intangibles	$ 700
Viscount Systems, Inc.
Business Acquisition [Line Items]
Accounts receivable				$ 636
Inventory				276
Prepaid expenses and other current assets				29
Property and equipment				190
Operating lease ROU assets				550
Finite-lived intangibles				1,670
Total identifiable assets acquired				3,351
Accounts payable				(372)
Operating lease liabilities				(61)
Accrued expenses and liabilities				(120)
Deferred revenue				(34)
Earn-out liability		$ (200)		(200)
Other current liabilities				(326)
Long-term operating lease liabilities				(489)
Total liabilities assumed				(1,602)
Net identifiable assets acquired				1,749
Goodwill				1,173
Purchase price				2,922
Viscount Systems, Inc. | Trademarks
Business Acquisition [Line Items]
Finite-lived intangibles				160
Viscount Systems, Inc. | Customer Relationships
Business Acquisition [Line Items]
Finite-lived intangibles				710
Viscount Systems, Inc. | Developed Technology
Business Acquisition [Line Items]
Finite-lived intangibles				$ 800