Fair Value Measurements (Details) - USD ($) $ in Thousands		Oct. 01, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value		$ 187,751	$ 203,965
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net current assets and current liabilities, fair value		187,533	204,004
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net current assets and current liabilities, fair value		48,839	65,946
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net current assets and current liabilities, fair value		138,694	138,058
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net current assets and current liabilities, fair value		0	0
Commercial papers
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value		24,550	9,996
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value		10,884	9,074
U.S. treasury bills and notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value		37,955	56,872
Securities and obligations of U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value		114,362	128,023
Reported Value Measurement [Member] | Commercial papers | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	24,550	9,996
Reported Value Measurement [Member] | Commercial papers | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	0	0
Reported Value Measurement [Member] | Commercial papers | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	24,550	9,996
Reported Value Measurement [Member] | Commercial papers | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	0	0
Reported Value Measurement [Member] | Money market funds | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	10,884	9,074
Reported Value Measurement [Member] | Money market funds | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	10,884	9,074
Reported Value Measurement [Member] | Money market funds | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	0	0
Reported Value Measurement [Member] | Money market funds | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	0	0
Reported Value Measurement [Member] | U.S. treasury bills and notes | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	37,955	56,872
Reported Value Measurement [Member] | U.S. treasury bills and notes | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	37,955	56,872
Reported Value Measurement [Member] | U.S. treasury bills and notes | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	0	0
Reported Value Measurement [Member] | U.S. treasury bills and notes | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	0	0
Reported Value Measurement [Member] | Securities and obligations of U.S. government agencies | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	114,362	128,023
Reported Value Measurement [Member] | Securities and obligations of U.S. government agencies | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	0	0
Reported Value Measurement [Member] | Securities and obligations of U.S. government agencies | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	114,362	128,023
Reported Value Measurement [Member] | Securities and obligations of U.S. government agencies | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	0	0
Reported Value Measurement [Member] | Available-for-sale securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	187,751	203,965
Reported Value Measurement [Member] | Available-for-sale securities | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	48,839	65,946
Reported Value Measurement [Member] | Available-for-sale securities | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	138,912	138,019
Reported Value Measurement [Member] | Available-for-sale securities | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	[1]	0	0
Designated as Hedging Instrument | Foreign Exchange Forward | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency derivatives, other current asset	[2]	0	43
Foreign currency derivatives, other current liabilities	[3]	(218)	(4)
Designated as Hedging Instrument | Foreign Exchange Forward | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency derivatives, other current asset	[2]	0	0
Foreign currency derivatives, other current liabilities	[3]	0	0
Designated as Hedging Instrument | Foreign Exchange Forward | Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency derivatives, other current asset	[2]	0	43
Foreign currency derivatives, other current liabilities	[3]	(218)	(4)
Designated as Hedging Instrument | Foreign Exchange Forward | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency derivatives, other current asset	[2]	0	0
Foreign currency derivatives, other current liabilities	[3]	$ 0	$ 0

[1] Included in cash and cash equivalents and short-term investments on our condensed consolidated balance sheets. See “Investments” in Note 7 for further details.

[2] Included in other current assets on our condensed consolidated balance sheets. Consisted of forward foreign exchange contracts for Japanese yen. See “Derivative Instruments and Hedging” in Note 8 for further details.

[3] Included in other current liabilities on our condensed consolidated balance sheets. Consisted of forward foreign exchange contracts for Japanese yen. See “Derivative Instruments and Hedging” in Note 8 for further details.