Fair Value Measurements (Details) - USD ($) $ in Thousands		Apr. 01, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value		$ 178,526	$ 183,115
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		178,527	183,115
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		12,666	31,727
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		165,861	151,388
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		31,679	23,684
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value		2,189	2,266
U.S. treasury bills and notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value		10,477	29,461
Securities and obligations of U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value		134,181	127,704
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]	31,679	23,684
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]	31,679	23,684
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]	2,189	2,266
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]	2,189	2,266
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]	10,477	29,461
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]	10,477	29,461
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]	134,181	127,704
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]	134,181	127,704
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]	178,526	183,115
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]	12,666	31,727
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]	165,860	151,388
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]	2	4
Foreign currency derivatives, other current liabilities	[3]	(1)	(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]	2	4
Foreign currency derivatives, other current liabilities	[3]	(1)	(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.