Fair Value Measurement - Reconciliation of the Beginning and Ending Level 3 Net Liabilities (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Payment of contingent earnout consideration		$ (5,189)	$ (2,214)
Adjustment to estimated fair value of contingent earnout consideration (included within Selling, general and administrative expense)	$ 928	(604)	928
Accretion of contingent earnout consideration (included within other expense, net)		(275)	$ (1,246)
Significant Unobservable Inputs (Level 3) [Member] | Zero2Ten and Branchbird Contingent Earnout Consideration [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		8,089
Payment of contingent earnout consideration		(8,132)
Adjustment to estimated fair value of contingent earnout consideration (included within Selling, general and administrative expense)		604
Accretion of contingent earnout consideration (included within other expense, net)		275
Ending balance		$ 836