Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Jun. 29, 2013		Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	$ 251,925		$ 251,878
Fair Value, Measurements, Recurring | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net current assets and current liabilities, fair value	251,914		251,875
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	11,415		15,107
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	240,499		236,768
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	9,099		19,996
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	11,415		15,107
U.S. treasury bills and notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	6,018		6,045
Securities and obligations of U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	225,393		210,730
Cash and Cash Equivalents and Short-term Investments | Commercial papers | Fair Value, Measurements, Recurring | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	9,099	[1]	19,996	[1]
Cash and Cash Equivalents and Short-term Investments | 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	0	[1]	0	[1]
Cash and Cash Equivalents and Short-term Investments | 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	9,099	[1]	19,996	[1]
Cash and Cash Equivalents and Short-term Investments | 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	0	[1]	0	[1]
Cash and Cash Equivalents and Short-term Investments | Money market funds | Fair Value, Measurements, Recurring | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	11,415	[1]	15,107	[1]
Cash and Cash Equivalents and Short-term Investments | 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	11,415	[1]	15,107	[1]
Cash and Cash Equivalents and Short-term Investments | 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	0	[1]	0	[1]
Cash and Cash Equivalents and Short-term Investments | 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	0	[1]	0	[1]
Cash and Cash Equivalents and Short-term Investments | U.S. treasury bills and notes | Fair Value, Measurements, Recurring | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	6,018	[1]	6,045	[1]
Cash and Cash Equivalents and Short-term Investments | 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	0	[1]	0	[1]
Cash and Cash Equivalents and Short-term Investments | 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	6,018	[1]	6,045	[1]
Cash and Cash Equivalents and Short-term Investments | 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	0	[1]	0	[1]
Cash and Cash Equivalents and Short-term Investments | Securities and obligations of U.S. government agencies | Fair Value, Measurements, Recurring | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	225,393	[1]	210,730	[1]
Cash and Cash Equivalents and Short-term Investments | 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	0	[1]	0	[1]
Cash and Cash Equivalents and Short-term Investments | 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	225,393	[1]	210,730	[1]
Cash and Cash Equivalents and Short-term Investments | 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	0	[1]	0	[1]
Cash and Cash Equivalents and Short-term Investments | Available-for-sale securities | Fair Value, Measurements, Recurring | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total, fair value	251,925	[1]	251,878	[1]
Cash and Cash Equivalents and Short-term Investments | 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	11,415	[1]	15,107	[1]
Cash and Cash Equivalents and Short-term Investments | 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	240,510	[1]	236,771	[1]
Cash and Cash Equivalents and Short-term Investments | 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	0	[1]	0	[1]
Designated as Hedging Instrument | Foreign Exchange Forward | Fair Value, Measurements, Recurring | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency derivatives, other current asset	8	[2]	28	[2]
Foreign currency derivatives, other current liabilities	(19)	[3]	(31)	[3]
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	0	[2]	0	[2]
Foreign currency derivatives, other current liabilities	0	[3]	0	[3]
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	8	[2]	28	[2]
Foreign currency derivatives, other current liabilities	(19)	[3]	(31)	[3]
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	0	[2]	0	[2]
Foreign currency derivatives, other current liabilities	$ 0	[3]	$ 0	[3]

[1] Included in cash and cash equivalents and short-term investments on our condensed consolidated balance sheets. See “Investments” in Note 6 for further details.

[2] Included in other current assets on our condensed consolidated balance sheets. Consisted of forward foreign exchange contracts for the Japanese yen. See “Derivative Instruments and Hedging” in Note 7 for further details.

[3] Included in other current liabilities on our condensed consolidated balance sheets. Consisted of forward foreign exchange contracts for the Japanese yen. See “Derivative Instruments and Hedging” in Note 7 for further details.