Financial Instruments - Additional Information (Details) - USD ($) |
12 Months Ended | |
|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Derivative [Line Items] | ||
| Accrued interest | $ 5,109,000 | $ 2,015 |
| Foreign exchange forward contracts | ||
| Derivative [Line Items] | ||
| Foreign exchange forward contracts, notional value | 276,696,000 | 182,464,000 |
| Foreign exchange forward contracts | Cash Flow Hedging | ||
| Derivative [Line Items] | ||
| Realized gains and losses related to the maturity of foreign exchange forward contracts | (4,170,000) | $ 3,398,000 |
| Foreign exchange forward contracts | Cash Flow Hedging | Other Current Liabilities | ||
| Derivative [Line Items] | ||
| Unrealized losses related to the effective portion of changes in the fair value of foreign exchange forward contracts | $ (12,216,000) | |