Fair Value Measurements (Schedule Of Fair Value Of Assets And Liabilities Measured On Recurring Basis) (Details) - USD ($) $ in Thousands | Sep. 30, 2016 | Dec. 31, 2015 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | $ 241,402 | $ 213,591 |
Agency Bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | | 12,065 |
Corporate Bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 142,680 | 177,613 |
Certificates Of Deposit [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 32,149 | 3,500 |
Asset-backed Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 29,226 | |
Commercial Paper - Marketable Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 21,826 | 3,491 |
U.S. Government Bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 14,119 | 12,871 |
Municipal Bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 1,402 | 1,399 |
International Government Bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | | 1,459 |
Treasury Bills [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | | 1,193 |
Measured At Fair Value On Recurring Basis [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 241,402 | 213,591 |
Measured At Fair Value On Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 241,402 | 213,591 |
Measured At Fair Value On Recurring Basis [Member] | Equity Mutual Funds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair value of Assets | 2,206 | 2,264 |
Measured At Fair Value On Recurring Basis [Member] | Equity Mutual Funds [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair value of Assets | 2,206 | 2,264 |
Measured At Fair Value On Recurring Basis [Member] | Foreign Currency Exchange Contracts [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair value of Assets | 3,698 | 4,876 |
Fair value of Liabilities | 3,346 | 1,365 |
Measured At Fair Value On Recurring Basis [Member] | Foreign Currency Exchange Contracts [Member] | Significant Other Observable Inputs (Level 2) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair value of Assets | 3,698 | 4,876 |
Fair value of Liabilities | 3,346 | 1,365 |
Measured At Fair Value On Recurring Basis [Member] | Deferred Compensation [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair value of Liabilities | 2,206 | 2,264 |
Measured At Fair Value On Recurring Basis [Member] | Deferred Compensation [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair value of Liabilities | 2,206 | 2,264 |
Measured At Fair Value On Recurring Basis [Member] | Interest Rate Swaps [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair value of Liabilities | | 384 |
Measured At Fair Value On Recurring Basis [Member] | Interest Rate Swaps [Member] | Significant Other Observable Inputs (Level 2) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair value of Liabilities | | 384 |
Measured At Fair Value On Recurring Basis [Member] | Money Market Funds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair value of Assets | 7,532 | 15,490 |
Measured At Fair Value On Recurring Basis [Member] | Money Market Funds [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair value of Assets | 7,532 | 15,490 |
Measured At Fair Value On Recurring Basis [Member] | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair value of Assets | 1,000 | 1,800 |
Measured At Fair Value On Recurring Basis [Member] | Commercial Paper [Member] | Significant Other Observable Inputs (Level 2) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair value of Assets | 1,000 | 1,800 |
Measured At Fair Value On Recurring Basis [Member] | Agency Bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair value of Assets | | 1,999 |
Measured At Fair Value On Recurring Basis [Member] | Agency Bonds [Member] | Significant Other Observable Inputs (Level 2) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fair value of Assets | | 1,999 |
Measured At Fair Value On Recurring Basis [Member] | Corporate Bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 142,680 | 177,613 |
Measured At Fair Value On Recurring Basis [Member] | Corporate Bonds [Member] | Significant Other Observable Inputs (Level 2) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 142,680 | 177,613 |
Measured At Fair Value On Recurring Basis [Member] | Certificates Of Deposit [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 32,149 | 3,500 |
Measured At Fair Value On Recurring Basis [Member] | Certificates Of Deposit [Member] | Significant Other Observable Inputs (Level 2) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 32,149 | 3,500 |
Measured At Fair Value On Recurring Basis [Member] | Asset-backed Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 29,226 | |
Measured At Fair Value On Recurring Basis [Member] | Asset-backed Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 29,226 | |
Measured At Fair Value On Recurring Basis [Member] | Commercial Paper - Marketable Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 21,826 | 3,491 |
Measured At Fair Value On Recurring Basis [Member] | Commercial Paper - Marketable Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 21,826 | 3,491 |
Measured At Fair Value On Recurring Basis [Member] | U.S. Government Bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 14,119 | 12,871 |
Measured At Fair Value On Recurring Basis [Member] | U.S. Government Bonds [Member] | Significant Other Observable Inputs (Level 2) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 14,119 | 12,871 |
Measured At Fair Value On Recurring Basis [Member] | Agency Bonds- Marketable Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | | 12,065 |
Measured At Fair Value On Recurring Basis [Member] | Agency Bonds- Marketable Securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | | 12,065 |
Measured At Fair Value On Recurring Basis [Member] | Municipal Bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | 1,402 | 1,399 |
Measured At Fair Value On Recurring Basis [Member] | Municipal Bonds [Member] | Significant Other Observable Inputs (Level 2) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | $ 1,402 | 1,399 |
Measured At Fair Value On Recurring Basis [Member] | International Government Bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | | 1,459 |
Measured At Fair Value On Recurring Basis [Member] | International Government Bonds [Member] | Significant Other Observable Inputs (Level 2) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | | 1,459 |
Measured At Fair Value On Recurring Basis [Member] | Treasury Bills [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | | 1,193 |
Measured At Fair Value On Recurring Basis [Member] | Treasury Bills [Member] | Significant Other Observable Inputs (Level 2) [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Total marketable securities | | $ 1,193 |