Fair Value Of Financial Instruments (Details) (USD $) | Mar. 31, 2014 | Dec. 31, 2013 |
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 | $26,676 | ' |
Fair Value, Inputs, Level 1 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, fair value disclosure | 2,169 | 14,671 |
Fair Value, Inputs, Level 2 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Assets, fair value disclosure | 24,909 | 28,407 |
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 | 27,078 | 43,078 |
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 | 402 | 12,796 |
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 | 402 | 12,796 |
Short-term Investments [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Available-for-sale securities, fair value disclosure | 18,442 | 18,840 |
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 | 8,747 | 6,772 |
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 | 8,747 | 6,772 |
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 | 8,747 | 6,772 |
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 | 1,501 | 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 | 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 | 1,501 | 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 | 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 | 1,501 | 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 | 6,172 | 8,870 |
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 | 6,172 | 8,870 |
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 | 6,172 | 8,870 |
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 | 1,000 | 999 |
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 | 1,000 | 999 |
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 | 1,022 | 1,198 |
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 | 1,022 | 1,198 |
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 | 1,022 | 1,198 |
Long-term Investments [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Available-for-sale securities, fair value disclosure | 8,234 | 11,442 |
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 | 3,700 | 6,956 |
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 | 3,700 | 6,956 |
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 | 3,700 | 6,956 |
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 | 1,012 | 1,014 |
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 | 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 | 1,012 | 1,014 |
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 | 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 | 1,012 | 1,014 |
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 | 2,777 | 2,795 |
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 | 2,777 | 2,795 |
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 | 2,777 | 2,795 |
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 | 745 | 677 |
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 | 745 | 677 |
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 | 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 | 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 | $745 | $677 |