Summary of Financial Assets Measured at Fair Value on Recurring Basis (Details) (USD $)
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Sep. 30, 2014
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Dec. 31, 2013
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | $ 380,837,000 | $ 229,018,000 |
Fair Value, Measurements, Recurring [Member]
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Assets, Fair Value Disclosure | 485,686,000 | 390,149,000 |
Fair Value, Measurements, Recurring [Member] | Israeli Severance Funds
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Other assets | 2,371,000 | 2,193,000 |
Fair Value, Measurements, Recurring [Member] | Cash Equivalents | Money market funds
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Cash equivalents | 74,985,000 | 143,540,000 |
Fair Value, Measurements, Recurring [Member] | Cash Equivalents | Commercial paper
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Cash equivalents | 27,493,000 | 15,398,000 |
Fair Value, Measurements, Recurring [Member] | Short-term Investments
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 244,820,000 | 127,040,000 |
Fair Value, Measurements, Recurring [Member] | Short-term Investments | Commercial paper
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 44,840,000 | 54,328,000 |
Fair Value, Measurements, Recurring [Member] | Short-term Investments | Corporate bonds
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||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 117,976,000 | 29,085,000 |
Fair Value, Measurements, Recurring [Member] | Short-term Investments | U.S. dollar dominated foreign corporate bonds
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 913,000 | 13,971,000 |
Fair Value, Measurements, Recurring [Member] | Short-term Investments | U.S. government agency bonds
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 47,589,000 | 16,703,000 |
Fair Value, Measurements, Recurring [Member] | Short-term Investments | Foreign bonds
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 913,000 | |
Fair Value, Measurements, Recurring [Member] | Short-term Investments | U.S. government treasury bonds
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 18,520,000 | |
Fair Value, Measurements, Recurring [Member] | Short-term Investments | Certificates of deposit
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 1,397,000 | |
Fair Value, Measurements, Recurring [Member] | Short-term Investments | Municipal securities
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 13,585,000 | 7,014,000 |
Fair Value, Measurements, Recurring [Member] | Short-term Investments | US Government Agency Bonds [Member]
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 47,589,000 | 16,703,000 |
Fair Value, Measurements, Recurring [Member] | Short-term Investments | Asset-backed securities
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||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 5,939,000 | |
Fair Value, Measurements, Recurring [Member] | Long-term Investments
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 136,017,000 | 101,978,000 |
Fair Value, Measurements, Recurring [Member] | Long-term Investments | Corporate bonds
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 73,403,000 | 23,313,000 |
Fair Value, Measurements, Recurring [Member] | Long-term Investments | U.S. dollar dominated foreign corporate bonds
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 19,495,000 | |
Fair Value, Measurements, Recurring [Member] | Long-term Investments | U.S. government agency bonds
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||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 28,888,000 | 38,118,000 |
Fair Value, Measurements, Recurring [Member] | Long-term Investments | Foreign bonds
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 19,495,000 | |
Fair Value, Measurements, Recurring [Member] | Long-term Investments | U.S. government treasury bonds
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 11,295,000 | 6,919,000 |
Fair Value, Measurements, Recurring [Member] | Long-term Investments | Municipal securities
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 10,005,000 | 8,331,000 |
Fair Value, Measurements, Recurring [Member] | Long-term Investments | US Government Agency Bonds [Member]
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||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 6,919,000 | |
Fair Value, Measurements, Recurring [Member] | Long-term Investments | Asset-backed securities
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 12,426,000 | 5,802,000 |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Assets, Fair Value Disclosure | 104,800,000 | 150,459,000 |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Israeli Severance Funds
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Other assets | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash Equivalents | Money market funds
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Cash equivalents | 74,985,000 | 143,540,000 |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash Equivalents | Commercial paper
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Cash equivalents | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term Investments | Commercial paper
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term Investments | Corporate bonds
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term Investments | U.S. dollar dominated foreign corporate bonds
|
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term Investments | Foreign bonds
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term Investments | U.S. government treasury bonds
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||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 18,520,000 | |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term Investments | Certificates of deposit
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term Investments | Municipal securities
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term Investments | US Government Agency Bonds [Member]
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term Investments | Asset-backed securities
|
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Long-term Investments | Corporate bonds
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||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Long-term Investments | U.S. government agency bonds
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||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Long-term Investments | Foreign bonds
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Long-term Investments | U.S. government treasury bonds
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 11,295,000 | |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Long-term Investments | Municipal securities
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Long-term Investments | US Government Agency Bonds [Member]
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 6,919,000 | |
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Long-term Investments | Asset-backed securities
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2)
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Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Assets, Fair Value Disclosure | 380,886,000 | 239,690,000 |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Israeli Severance Funds
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Other assets | 2,371,000 | 2,193,000 |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Cash Equivalents | Money market funds
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Cash equivalents | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Cash Equivalents | Commercial paper
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Cash equivalents | 27,493,000 | 15,398,000 |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Short-term Investments | Commercial paper
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 44,840,000 | 54,328,000 |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Short-term Investments | Corporate bonds
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 117,976,000 | 29,085,000 |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Short-term Investments | U.S. dollar dominated foreign corporate bonds
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 13,971,000 | |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Short-term Investments | Foreign bonds
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 913,000 | |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Short-term Investments | U.S. government treasury bonds
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Short-term Investments | Certificates of deposit
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 1,397,000 | |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Short-term Investments | Municipal securities
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 13,585,000 | 7,014,000 |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Short-term Investments | US Government Agency Bonds [Member]
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 47,589,000 | 16,703,000 |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Short-term Investments | Asset-backed securities
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 5,939,000 | |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Long-term Investments | Corporate bonds
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 73,403,000 | 23,313,000 |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Long-term Investments | U.S. government agency bonds
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 28,888,000 | 38,118,000 |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Long-term Investments | Foreign bonds
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 19,495,000 | |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Long-term Investments | U.S. government treasury bonds
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Long-term Investments | Municipal securities
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 10,005,000 | 8,331,000 |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Long-term Investments | US Government Agency Bonds [Member]
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | 0 | |
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) | Long-term Investments | Asset-backed securities
|
||
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] | ||
Investments | $ 12,426,000 | $ 5,802,000 |