Fair Value Measurement (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Assets:
Short-term investments	$ 196,619	$ 181,677
Foreign currency forward exchange contracts not accounted for using hedge accounting		157
Assets		181,834
Liabilities:
Foreign currency forward exchange contracts not accounted for using hedge accounting	703
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
Liabilities:
Foreign currency forward exchange contracts not accounted for using hedge accounting
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Short-term investments	196,619	181,677
Foreign currency forward exchange contracts not accounted for using hedge accounting		157
Assets		181,834
Liabilities:
Foreign currency forward exchange contracts not accounted for using hedge accounting	703
Significant Unobservable Inputs (Level 3) [Member]
Assets:
Short-term investments
Foreign currency forward exchange contracts not accounted for using hedge accounting
Assets
Liabilities:
Foreign currency forward exchange contracts not accounted for using hedge accounting