Financial Instruments (Investment and Derivative Information) (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2017 |
Jun. 30, 2016 |
Jun. 30, 2017 |
Jun. 30, 2016 |
|
| Foreign exchange contracts | ||||
| Fair Value Measurements | ||||
| Assets related to derivative instruments | $ 0 | $ 0 | ||
| Liabilities related to derivative instruments | 0 | 0 | ||
| Notional principal amount of foreign exchange contracts | 15,100 | 15,100 | ||
| Foreign exchange contracts | Other income (expense), net | Not designated as hedging instrument | ||||
| Fair Value Measurements | ||||
| Foreign exchange forward contracts | $ (405) | $ 359 | $ (932) | $ 43 |
| Minimum | ||||
| Fair Value Measurements | ||||
| Maturity period of long-term investments | 1 year | |||
| Maximum | ||||
| Fair Value Measurements | ||||
| Maturity period of long-term investments | 2 years | |||