Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Presentation of fair value of financial assets using the inputs
Total financial assets	$ 14,150	$ 13,866
Money market funds
Presentation of fair value of financial assets using the inputs
Total financial assets	14,150	13,866
Quoted Prices in Active Markets for Identical Assets (Level 1)
Presentation of fair value of financial assets using the inputs
Total financial assets	14,150	13,866
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds
Presentation of fair value of financial assets using the inputs
Total financial assets	14,150	13,866
Significant Other Observable Inputs (Level 2)
Presentation of fair value of financial assets using the inputs
Total financial assets
Significant Other Observable Inputs (Level 2) | Money market funds
Presentation of fair value of financial assets using the inputs
Total financial assets
Significant Unobservable Inputs (Level 3)
Presentation of fair value of financial assets using the inputs
Total financial assets
Significant Unobservable Inputs (Level 3) | Money market funds
Presentation of fair value of financial assets using the inputs
Total financial assets