Fair Value Measurement (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Assets:
Short-term investments	$ 119,682
Foreign currency forward exchange contracts not accounted for using hedge accounting	182	784
Assets	119,864
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Short-term investments
Foreign currency forward exchange contracts not accounted for using hedge accounting
Assets
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Short-term investments	119,682
Foreign currency forward exchange contracts not accounted for using hedge accounting	182	784
Assets	119,864
Significant Unobservable Inputs (Level 3) [Member]
Assets:
Short-term investments
Foreign currency forward exchange contracts not accounted for using hedge accounting
Assets