Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		12 Months Ended
	Dec. 31, 2017 USD ($) shares	Mar. 31, 2017 USD ($)	Dec. 31, 2018	Dec. 31, 2017 USD ($) Segment Unit Customer Occurrence_Per_Year shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($) shares
Summary Of Significant Accounting Policies [Line Items]
Capitalized amount in product development cost				$ 0	$ 0
Amortization from capitalized software development costs				$ 7,000	188,000	$ 191,000
Number of reportable segments for business activities | Segment				3
Number of reporting units for goodwill allocation | Unit				3
Standard payment terms to customers				30 days
Losses recognized on fixed-price contracts				$ 0	$ 0	$ 0
Maintenance fee revenue recognition period				1 year
U.S. federal corporate tax rate				34.00%	34.00%	34.00%
Number of occurrences of transition tax | Occurrence_Per_Year				1
Taxable income associated with one-time transition tax on earnings of certain foreign subsidiaries				$ 266,000
Diluted computation increased | shares				602,000	0	63,000
Share-based awards outstanding under equity plans | shares	1,462,365			1,462,365	2,850,330	3,749,783
Excess customer balance from receivables				$ 0	$ 0
Customer balances excess percentage of total receivables balance				10.00%	10.00%
Customer threshold percentage of total receivables or total service revenue	10.00%			10.00%	10.00%	10.00%
Number of largest customers | Customer				5
Cumulative adjustment to retained earnings		$ 1,400,000
Zero Two Ten Contingent Earnout Consideration [Member]
Summary Of Significant Accounting Policies [Line Items]
Reclassification from financing activities to operating activities					$ 1,000,000
ASU 2016-09 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cumulative adjustment to retained earnings	$ 1,400,000
Scenario Plan [Member]
Summary Of Significant Accounting Policies [Line Items]
U.S. federal corporate tax rate			21.00%
Revenue from Rights Concentration Risk [Member] | Sales Revenue, Net [Member]
Summary Of Significant Accounting Policies [Line Items]
Aggregate service revenue				13.90%	15.20%	11.80%
Option Plans [Member]
Summary Of Significant Accounting Policies [Line Items]
Diluted computation increased | shares				662,000	2,000,000	1,900,000
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives				3 years
Acquired intangible assets useful lives				3 years
Warranty period on fixed-price contracts				30 days
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful lives				10 years
Estimated economic life of product				3 years
Acquired intangible assets useful lives				6 years
Warranty period on fixed-price contracts				60 days
U.S. federal corporate tax rate				35.00%