Fair Value Of Financial Instruments (Details) (USD $) | Sep. 30, 2013 | Dec. 31, 2012 |
In Thousands, unless otherwise specified |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | $31,646 | |
Fair Value, Inputs, Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value disclosure | 13,168 | 19,345 |
Fair Value, Inputs, Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value disclosure | 29,835 | 34,633 |
Fair Value, Inputs, Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value disclosure | 0 | 0 |
Liabilities, fair value disclosure | 0 | 0 |
Fair Value Disclosure [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets, fair value disclosure | 43,003 | 53,978 |
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents, fair value disclosure | 11,357 | 18,274 |
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents, fair value disclosure | 0 | 0 |
Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents, fair value disclosure | 0 | 0 |
Money Market Funds [Member] | Fair Value Disclosure [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents, fair value disclosure | 11,357 | 18,274 |
Short-term Investments [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 18,980 | 22,563 |
Short-term Investments [Member] | U.S. Agency securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 7,770 | 11,077 |
Short-term Investments [Member] | U.S. Agency securities [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | 0 |
Short-term Investments [Member] | U.S. Agency securities [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 7,770 | 11,077 |
Short-term Investments [Member] | U.S. Agency securities [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | 0 |
Short-term Investments [Member] | U.S. Agency securities [Member] | Fair Value Disclosure [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 7,770 | 11,077 |
Short-term Investments [Member] | U.S. Treasury [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 1,001 | |
Short-term Investments [Member] | U.S. Treasury [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | |
Short-term Investments [Member] | U.S. Treasury [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 1,001 | |
Short-term Investments [Member] | U.S. Treasury [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | |
Short-term Investments [Member] | U.S. Treasury [Member] | Fair Value Disclosure [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 1,001 | |
Short-term Investments [Member] | Corporate bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 7,378 | 8,417 |
Short-term Investments [Member] | Corporate bonds [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | 0 |
Short-term Investments [Member] | Corporate bonds [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 7,378 | 8,417 |
Short-term Investments [Member] | Corporate bonds [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | 0 |
Short-term Investments [Member] | Corporate bonds [Member] | Fair Value Disclosure [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 7,378 | 8,417 |
Short-term Investments [Member] | Commercial Paper [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | 0 |
Short-term Investments [Member] | Commercial Paper [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 1,999 | 1,998 |
Short-term Investments [Member] | Commercial Paper [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | 0 |
Short-term Investments [Member] | Commercial Paper [Member] | Fair Value Disclosure [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 1,999 | 1,998 |
Short-term Investments [Member] | Certificates of Deposit [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 832 | 1,071 |
Short-term Investments [Member] | Certificates of Deposit [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 832 | 1,071 |
Short-term Investments [Member] | Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | 0 |
Short-term Investments [Member] | Certificates of Deposit [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | 0 |
Short-term Investments [Member] | Certificates of Deposit [Member] | Fair Value Disclosure [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 832 | 1,071 |
Long-term Investments [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 12,666 | 13,141 |
Long-term Investments [Member] | U.S. Agency securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 7,874 | 7,753 |
Long-term Investments [Member] | U.S. Agency securities [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | 0 |
Long-term Investments [Member] | U.S. Agency securities [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 7,874 | 7,753 |
Long-term Investments [Member] | U.S. Agency securities [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | 0 |
Long-term Investments [Member] | U.S. Agency securities [Member] | Fair Value Disclosure [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 7,874 | 7,753 |
Long-term Investments [Member] | U.S. Treasury [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 1,016 | |
Long-term Investments [Member] | U.S. Treasury [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | |
Long-term Investments [Member] | U.S. Treasury [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 1,016 | |
Long-term Investments [Member] | U.S. Treasury [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | |
Long-term Investments [Member] | U.S. Treasury [Member] | Fair Value Disclosure [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 1,016 | |
Long-term Investments [Member] | Corporate bonds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 2,797 | 5,388 |
Long-term Investments [Member] | Corporate bonds [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | 0 |
Long-term Investments [Member] | Corporate bonds [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 2,797 | 5,388 |
Long-term Investments [Member] | Corporate bonds [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | 0 |
Long-term Investments [Member] | Corporate bonds [Member] | Fair Value Disclosure [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 2,797 | 5,388 |
Long-term Investments [Member] | Certificates of Deposit [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 979 | |
Long-term Investments [Member] | Certificates of Deposit [Member] | Fair Value, Inputs, Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 979 | |
Long-term Investments [Member] | Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | |
Long-term Investments [Member] | Certificates of Deposit [Member] | Fair Value, Inputs, Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | 0 | |
Long-term Investments [Member] | Certificates of Deposit [Member] | Fair Value Disclosure [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, fair value disclosure | $979 | |