Financial Instruments - Schedule of Fair Value Hierarchy (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Presentation of fair value of financial assets using the inputs
Total financial assets	$ 13,866	$ 5,665
Money market funds
Presentation of fair value of financial assets using the inputs
Total financial assets	13,866	5,665
Quoted Prices in Active Markets for Identical Assets (Level 1)
Presentation of fair value of financial assets using the inputs
Total financial assets	13,866	5,665
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	13,866	5,665
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