Fair Value Measurements - Fair Value Liabilities Measured on Recurring Basis (Detail) - Fair Value, Inputs, Level 3 [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, Beginning Balance	$ 901
Fair value adjustments	(901)
Zindagi [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, Beginning Balance	180
Fair value adjustments	(180)
PuzzleSocial [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability, Beginning Balance	721
Fair value adjustments	$ (721)