Financial Instruments (Investment and Derivative Information) (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Foreign Exchange Contract        
Fair Value Measurements        
Assets related to derivative instruments $ 0   $ 0  
Liabilities related to derivative instruments 0   0  
Foreign Exchange Contract | Other income (expense), net | Not Designated as Hedging Instrument        
Fair Value Measurements        
Foreign exchange contracts $ 359 $ (100) $ 43 $ (100)
Minimum        
Fair Value Measurements        
Maturity period of long-term investments     1 year  
Maximum        
Fair Value Measurements        
Maturity period of long-term investments     2 years