Financial Assets Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments Commercial paper	$ 0	$ 19,995
Total assets measured and recorded at fair value	168,078	153,001
Foreign exchange forward contracts	514	4,603
Contingent consideration obligation	1,282	0
Total liabilities measured and recorded at fair value	1,796	4,603
Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	49,988	59,980
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	118,090	73,026
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments Commercial paper	0	0
Total assets measured and recorded at fair value	118,090	73,026
Foreign exchange forward contracts	0	0
Contingent consideration obligation	0	0
Total liabilities measured and recorded at fair value	0	0
Fair Value, Inputs, Level 1 | Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	0	0
Fair Value, Inputs, Level 1 | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	118,090	73,026
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments Commercial paper	0	19,995
Total assets measured and recorded at fair value	49,988	79,975
Foreign exchange forward contracts	514	4,603
Contingent consideration obligation	0	0
Total liabilities measured and recorded at fair value	514	4,603
Fair Value, Inputs, Level 2 | Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	49,988	59,980
Fair Value, Inputs, Level 2 | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	0	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term investments Commercial paper	0	0
Total assets measured and recorded at fair value	0	0
Foreign exchange forward contracts	0	0
Contingent consideration obligation	1,282	0
Total liabilities measured and recorded at fair value	1,282	0
Fair Value, Inputs, Level 3 [Member] | Commercial Paper
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	0	0
Fair Value, Inputs, Level 3 [Member] | Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Cash equivalents	$ 0	$ 0