Acquisitions - Summary of Purchase Price Allocation (Detail) - USD ($) $ in Thousands	Jun. 11, 2018	Apr. 04, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill			$ 46,511	$ 74,292	$ 70,729
Smadex
Business Acquisition [Line Items]
Purchase price consideration	$ 3,500
Accounts receivable	900
Other current assets	400
Intangible assets subject to amortization	2,000
Goodwill	3,600
Current liabilities	(2,800)
Long-term liabilities	(200)
Deferred tax	$ (400)
Headway
Business Acquisition [Line Items]
Purchase price consideration		$ 8,200
Accounts receivable		19,800
Intangible assets subject to amortization		15,900
Goodwill		16,100
Current liabilities		(23,700)
Deferred tax		$ (4,000)