Fair Value of Assets and Liabilities (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Assets and liabilities measured and recorded in the financial statements at fair value on a recurring basis
Total assets	$ 6,102	$ 9,990
Total liabilities
Money market fund [Member]
Assets and liabilities measured and recorded in the financial statements at fair value on a recurring basis
Total assets	6,102	9,990
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member]
Assets and liabilities measured and recorded in the financial statements at fair value on a recurring basis
Total assets	6,102	9,990
Total liabilities
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) [Member] | Money market fund [Member]
Assets and liabilities measured and recorded in the financial statements at fair value on a recurring basis
Total assets	6,102	9,990
Significant Other Observable Inputs (Level 2) [Member]
Assets and liabilities measured and recorded in the financial statements at fair value on a recurring basis
Total assets
Total liabilities
Significant Other Observable Inputs (Level 2) [Member] | Money market fund [Member]
Assets and liabilities measured and recorded in the financial statements at fair value on a recurring basis
Total assets
Significant Unobservable Inputs (Level 3) [Member]
Assets and liabilities measured and recorded in the financial statements at fair value on a recurring basis
Total assets
Total liabilities
Significant Unobservable Inputs (Level 3) [Member] | Money market fund [Member]
Assets and liabilities measured and recorded in the financial statements at fair value on a recurring basis
Total assets