Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value Based on Three-Tier Fair Value Hierarchy (Detail) - USD ($)	Jul. 03, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities, Fair Value Disclosure, Nonrecurring	$ 0
Assets, Fair Value Disclosure, Nonrecurring	0
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	59,246,000	$ 57,915,000
Total liabilities measured and recorded at fair value	81,000	7,000
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	29,530,000	25,727,000
Total liabilities measured and recorded at fair value	0	0
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	29,716,000	32,188,000
Total liabilities measured and recorded at fair value	81,000	7,000
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Total liabilities measured and recorded at fair value	0	0
Cash equivalents [Member] | Money market funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	25,956,000	23,121,000
Cash equivalents [Member] | Level 1 [Member] | Money market funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	25,956,000	23,121,000
Cash equivalents [Member] | Level 2 [Member] | Money market funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Cash equivalents [Member] | Level 3 [Member] | Money market funds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Short-term investments [Member] | State, municipal and local government agencies bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	8,872,000	13,961,000
Short-term investments [Member] | Corporate bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	20,162,000	17,886,000
Short-term investments [Member] | Level 1 [Member] | State, municipal and local government agencies bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Short-term investments [Member] | Level 1 [Member] | Corporate bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Short-term investments [Member] | Level 2 [Member] | State, municipal and local government agencies bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	8,872,000	13,961,000
Short-term investments [Member] | Level 2 [Member] | Corporate bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	20,162,000	17,886,000
Short-term investments [Member] | Level 3 [Member] | State, municipal and local government agencies bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Short-term investments [Member] | Level 3 [Member] | Corporate bonds [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Prepaids and other current assets [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	682,000	341,000
Prepaids and other current assets [Member] | Level 1 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Prepaids and other current assets [Member] | Level 2 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	682,000	341,000
Prepaids and other current assets [Member] | Level 3 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	0	0
Cost-method Investments [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	3,574,000	2,606,000
Cost-method Investments [Member] | Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured and recorded at fair value	3,574,000	2,606,000
Accrued Liabilities [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured and recorded at fair value	81,000	7,000
Accrued Liabilities [Member] | Level 1 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured and recorded at fair value	0	0
Accrued Liabilities [Member] | Level 2 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured and recorded at fair value	81,000	7,000
Accrued Liabilities [Member] | Level 3 [Member] | Foreign exchange forward contracts [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured and recorded at fair value	$ 0	$ 0