Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value Based on Three-Tier Fair Value Hierarchy (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	$ 131,462		$ 166,392
Total liabilities measured and recorded at fair value	195		143
Cash equivalents [Member] | Money market funds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	51,014		54,923
Cash equivalents [Member] | Corporate bonds [Member] | Maturity less than 90 days [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value			3,614
Cash equivalents [Member] | U.S. federal government bonds [Member] | Maturity less than 90 days [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value			3,005
Short-term investments [Member] | Corporate bonds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	33,496		31,562
Short-term investments [Member] | U.S. federal government bonds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	4,008		2,003
Short-term investments [Member] | Certificates of deposit [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value			1,603
Short-term investments [Member] | State, municipal and local government agencies bonds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	40,449		59,050
Short-term investments [Member] | Commercial paper [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	2,299		10,288
Prepaids and other current assets [Member] | Foreign exchange forward contracts [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	196	[1]	344	[1]
Accrued liabilities [Member] | Foreign exchange forward contracts [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total liabilities measured and recorded at fair value	195	[1]	143	[1]
Level 1 [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	55,022		59,931
Total liabilities measured and recorded at fair value	0		0
Level 1 [Member] | Cash equivalents [Member] | Money market funds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	51,014		54,923
Level 1 [Member] | Cash equivalents [Member] | Corporate bonds [Member] | Maturity less than 90 days [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value			0
Level 1 [Member] | Cash equivalents [Member] | U.S. federal government bonds [Member] | Maturity less than 90 days [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value			3,005
Level 1 [Member] | Short-term investments [Member] | Corporate bonds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	0		0
Level 1 [Member] | Short-term investments [Member] | U.S. federal government bonds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	4,008		2,003
Level 1 [Member] | Short-term investments [Member] | Certificates of deposit [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value			0
Level 1 [Member] | Short-term investments [Member] | State, municipal and local government agencies bonds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	0		0
Level 1 [Member] | Short-term investments [Member] | Commercial paper [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	0		0
Level 1 [Member] | Prepaids and other current assets [Member] | Foreign exchange forward contracts [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	0	[1]	0	[1]
Level 1 [Member] | Accrued liabilities [Member] | Foreign exchange forward contracts [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total liabilities measured and recorded at fair value	0	[1]	0	[1]
Level 2 [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	76,440		106,461
Total liabilities measured and recorded at fair value	195		143
Level 2 [Member] | Cash equivalents [Member] | Money market funds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	0		0
Level 2 [Member] | Cash equivalents [Member] | Corporate bonds [Member] | Maturity less than 90 days [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value			3,614
Level 2 [Member] | Cash equivalents [Member] | U.S. federal government bonds [Member] | Maturity less than 90 days [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value			0
Level 2 [Member] | Short-term investments [Member] | Corporate bonds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	33,496		31,562
Level 2 [Member] | Short-term investments [Member] | U.S. federal government bonds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	0		0
Level 2 [Member] | Short-term investments [Member] | Certificates of deposit [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value			1,603
Level 2 [Member] | Short-term investments [Member] | State, municipal and local government agencies bonds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	40,449		59,050
Level 2 [Member] | Short-term investments [Member] | Commercial paper [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	2,299		10,288
Level 2 [Member] | Prepaids and other current assets [Member] | Foreign exchange forward contracts [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	196	[1]	344	[1]
Level 2 [Member] | Accrued liabilities [Member] | Foreign exchange forward contracts [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total liabilities measured and recorded at fair value	195	[1]	143	[1]
Level 3 [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	0		0
Total liabilities measured and recorded at fair value	0		0
Level 3 [Member] | Cash equivalents [Member] | Money market funds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	0		0
Level 3 [Member] | Cash equivalents [Member] | Corporate bonds [Member] | Maturity less than 90 days [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value			0
Level 3 [Member] | Cash equivalents [Member] | U.S. federal government bonds [Member] | Maturity less than 90 days [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value			0
Level 3 [Member] | Short-term investments [Member] | Corporate bonds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	0		0
Level 3 [Member] | Short-term investments [Member] | U.S. federal government bonds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	0		0
Level 3 [Member] | Short-term investments [Member] | Certificates of deposit [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value			0
Level 3 [Member] | Short-term investments [Member] | State, municipal and local government agencies bonds [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	0		0
Level 3 [Member] | Short-term investments [Member] | Commercial paper [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	0		0
Level 3 [Member] | Prepaids and other current assets [Member] | Foreign exchange forward contracts [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total assets measured and recorded at fair value	0	[1]	0	[1]
Level 3 [Member] | Accrued liabilities [Member] | Foreign exchange forward contracts [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Total liabilities measured and recorded at fair value	$ 0	[1]	$ 0	[1]

[1] Derivative assets and liabilities represent forward currency exchange contracts. The Company enters into these contracts to minimize the short-term impact of foreign currency exchange rates fluctuations primarily from trade and inter-company receivables and payables.