Business Combinations - Summary of Preliminary Purchase Price Allocation (Detail) - USD ($) $ in Thousands			9 Months Ended
	Aug. 17, 2015	Mar. 13, 2015	Sep. 30, 2015
Branchbird [Member]
Business Acquisition [Line Items]
Customer relationships			5 years
Accounts receivable	$ 540
Other assets	16
Accounts payable and accrued expenses	(86)
Customer relationships	2,100
Goodwill (deductible for tax purposes)	1,613
Total purchase price	$ 4,183
Zero2Ten [Member]
Business Acquisition [Line Items]
Customer relationships		5 years
Accounts receivable		$ 1,596
Other assets		142
Deferred revenue		(1,158)
Accounts payable and accrued expenses		(580)
Customer relationships		2,800
Goodwill (deductible for tax purposes)		6,210
Total purchase price		$ 9,010