Fair Value Measurements - Additional Information (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Asset measured and recognized at fair value on recurring basis	$ 0	$ 0
idOnDemand, Inc.
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contingent consideration related to the acquisition	5,000,000	5,000,000
Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalent at recurring basis	0	0
Fair Value Measurements, Non-recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value liabilities measured and recognized	0	0
Fair Value Measurements, Non-recurring | Fair Value, Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Privately-held investments measured at fair value	$ 300,000	$ 0