Marketable Securities and Fair Value Disclosures - Fair Value of Assets and Liabilities Measured on Recurring Basis (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 6,309,000	$ 5,870,000
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	96,609,000	100,716,000
Financial liabilities	17,871,000	23,838,000
Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank time deposits	83,287,000	79,662,000
Fair Value, Measurements, Recurring [Member] | Cash and cash equivalents [Member] | Money market fund deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	6,182,000	14,154,000
Fair Value, Measurements, Recurring [Member] | Marketable securities, current portion [Member] | Mutual funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	6,309,000	5,870,000
Fair Value, Measurements, Recurring [Member] | Prepaid expenses and other current assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		129,000
Indemnification assets associated with acquisitions, current	604,000	304,000
Fair Value, Measurements, Recurring [Member] | Other assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Indemnification assets associated with acquisitions, noncurrent	227,000	597,000
Fair Value, Measurements, Recurring [Member] | Accrued expenses [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange option contracts	90,000	175,000
Contingent consideration liabilities associated with acquisitions	10,155,000	11,237,000
Fair Value, Measurements, Recurring [Member] | Other long-term liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liabilities associated with acquisitions	7,626,000	12,426,000
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	12,491,000	20,024,000
Financial liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Cash and cash equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank time deposits	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Cash and cash equivalents [Member] | Money market fund deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	6,182,000	14,154,000
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Marketable securities, current portion [Member] | Mutual funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	6,309,000	5,870,000
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Prepaid expenses and other current assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		0
Indemnification assets associated with acquisitions, current	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Other assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Indemnification assets associated with acquisitions, noncurrent	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Accrued expenses [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange option contracts	0	0
Contingent consideration liabilities associated with acquisitions	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Other long-term liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liabilities associated with acquisitions	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	83,287,000	79,791,000
Financial liabilities	90,000	175,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Cash and cash equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank time deposits	83,287,000	79,662,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Cash and cash equivalents [Member] | Money market fund deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Marketable securities, current portion [Member] | Mutual funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Prepaid expenses and other current assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		129,000
Indemnification assets associated with acquisitions, current	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Indemnification assets associated with acquisitions, noncurrent	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Accrued expenses [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange option contracts	90,000	175,000
Contingent consideration liabilities associated with acquisitions	0	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other long-term liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liabilities associated with acquisitions	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	831,000	901,000
Financial liabilities	17,781,000	23,663,000
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Cash and cash equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank time deposits	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Cash and cash equivalents [Member] | Money market fund deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Marketable securities, current portion [Member] | Mutual funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Prepaid expenses and other current assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset		0
Indemnification assets associated with acquisitions, current	604,000	304,000
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Indemnification assets associated with acquisitions, noncurrent	227,000	597,000
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Accrued expenses [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange option contracts	0	0
Contingent consideration liabilities associated with acquisitions	10,155,000	11,237,000
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other long-term liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liabilities associated with acquisitions	$ 7,626,000	$ 12,426,000