Fair Value Of Financial Instruments (Summary Of Valuation Of Company's Financial Instruments By Various Levels) (Details) (USD $) In Thousands, unless otherwise specified	Apr. 01, 2012		Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	$ 249,260		$ 170,878
Liabilities, Fair value	348		723
Quoted Market Prices In Active Markets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	248,899		169,641
Liabilities, Fair value	0		0
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	361		1,237
Liabilities, Fair value	348		723
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	0		0
Liabilities, Fair value	0		0
Foreign Currency Forward Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	361	[1]	1,237	[1]
Liabilities, Fair value	348	[2]	723	[2]
Foreign Currency Forward Contracts [Member] | Quoted Market Prices In Active Markets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	0	[1]	0	[1]
Liabilities, Fair value	0	[2]	0	[2]
Foreign Currency Forward Contracts [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	361	[1]	1,237	[1]
Liabilities, Fair value	348	[2]	723	[2]
Foreign Currency Forward Contracts [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	0	[1]	0	[1]
Liabilities, Fair value	0	[2]	0	[2]
Money Market Funds [Member] | Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	28,738		24,844
Money Market Funds [Member] | Cash Equivalents [Member] | Quoted Market Prices In Active Markets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	28,738		24,844
Money Market Funds [Member] | Cash Equivalents [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	0		0
Money Market Funds [Member] | Cash Equivalents [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	0		0
U.S. Treasuries [Member] | Available-For-Sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	219,978	[3]	144,703	[3]
U.S. Treasuries [Member] | Available-For-Sale Securities [Member] | Quoted Market Prices In Active Markets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	219,978	[3]	144,703	[3]
U.S. Treasuries [Member] | Available-For-Sale Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	0	[3]	0	[3]
U.S. Treasuries [Member] | Available-For-Sale Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	0	[3]	0	[3]
Certificates Of Deposits [Member] | Available-For-Sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	183	[3]	94	[3]
Certificates Of Deposits [Member] | Available-For-Sale Securities [Member] | Quoted Market Prices In Active Markets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	183	[3]	94
Certificates Of Deposits [Member] | Available-For-Sale Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	0	[3]	0	[3]
Certificates Of Deposits [Member] | Available-For-Sale Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair value	$ 0	[3]	$ 0	[3]

[1] Included in prepaid expenses and other current assets on the Company’s unaudited condensed consolidated balance sheet.

[2] Included in other accrued liabilities on the Company’s unaudited condensed consolidated balance sheet.

[3] Included in short-term investments on the Company’s unaudited condensed consolidated balance sheet.