Fair Value Measurement (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Financial assets:
Total financial assets	$ 4,084	$ 4,084
Money market investment [Member]
Financial assets:
Total financial assets	4,084	4,084
Quoted Prices in Active Markets for Identical Items (Level 1) [Member]
Financial assets:
Total financial assets	4,084	4,084
Quoted Prices in Active Markets for Identical Items (Level 1) [Member] | Money market investment [Member]
Financial assets:
Total financial assets	4,084	4,084
Significant Other Observable Inputs (Level 2) [Member]
Financial assets:
Total financial assets
Significant Other Observable Inputs (Level 2) [Member] | Money market investment [Member]
Financial assets:
Total financial assets
Significant Unobservable Inputs (Level 3) [Member]
Financial assets:
Total financial assets
Significant Unobservable Inputs (Level 3) [Member] | Money market investment [Member]
Financial assets:
Total financial assets