Acquisitions - Additional Information (Details) - USD ($) $ in Thousands					3 Months Ended	9 Months Ended
	May 18, 2018	May 01, 2018	Apr. 03, 2018	Jan. 27, 2017	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Business Acquisition [Line Items]
Purchase price of acquisition, cash						$ 35,857	$ 21,235
Goodwill					$ 53,132	$ 53,132		$ 31,328
UMS
Business Acquisition [Line Items]
Date of acquisition of business			Apr. 03, 2018
Purchase price of acquisition, cash			$ 31,900
Weighted average useful life of identified acquired intangible assets						4 years 8 months 4 days
Goodwill			$ 20,200		20,201	$ 20,201
Business acquisition transaction costs					0	400
Total purchase price						$ 31,884
UMS | Minimum
Business Acquisition [Line Items]
Estimated useful life						1 year
UMS | Maximum
Business Acquisition [Line Items]
Estimated useful life						5 years
UMS | Acquired Technology
Business Acquisition [Line Items]
Weighted average useful life of identified acquired intangible assets						3 years
UMS | Customer Relationships
Business Acquisition [Line Items]
Weighted average useful life of identified acquired intangible assets						5 years
UMS | Trade Names
Business Acquisition [Line Items]
Weighted average useful life of identified acquired intangible assets						1 year
PlanetRisk, Inc.
Business Acquisition [Line Items]
Date of acquisition of business		May 01, 2018
Purchase price of acquisition, cash		$ 2,000
Weighted average useful life of identified acquired intangible assets						4 years 9 months
Goodwill		$ 1,200			1,205	$ 1,205
Business acquisition transaction costs					0	100
Total purchase price						$ 2,021
PlanetRisk, Inc. | Minimum
Business Acquisition [Line Items]
Estimated useful life						3 years
PlanetRisk, Inc. | Maximum
Business Acquisition [Line Items]
Estimated useful life						5 years
PlanetRisk, Inc. | Acquired Technology
Business Acquisition [Line Items]
Weighted average useful life of identified acquired intangible assets						3 years
PlanetRisk, Inc. | Customer Relationships
Business Acquisition [Line Items]
Weighted average useful life of identified acquired intangible assets						5 years
Respond B.V.
Business Acquisition [Line Items]
Date of acquisition of business	May 18, 2018
Purchase price of acquisition, cash	$ 2,000
Weighted average useful life of identified acquired intangible assets						4 years 7 months 17 days
Goodwill	1,500				1,488	$ 1,488
Business acquisition transaction costs					$ 0	100
Note payable	400					383
Total purchase price	$ 2,300					$ 2,335
Respond B.V. | Minimum
Business Acquisition [Line Items]
Estimated useful life						1 year
Respond B.V. | Maximum
Business Acquisition [Line Items]
Estimated useful life						5 years
Respond B.V. | Acquired Technology
Business Acquisition [Line Items]
Weighted average useful life of identified acquired intangible assets						3 years
Respond B.V. | Customer Relationships
Business Acquisition [Line Items]
Weighted average useful life of identified acquired intangible assets						5 years
Respond B.V. | Trade Names
Business Acquisition [Line Items]
Weighted average useful life of identified acquired intangible assets						1 year
IDV Solutions LLC
Business Acquisition [Line Items]
Date of acquisition of business				Jan. 27, 2017
Purchase price of acquisition, cash				$ 21,200
Goodwill				$ 21,200