Derivatives - Foreign Currency Exchange Contracts (Details) - Not Designated as Hedging Instrument	3 Months Ended	12 Months Ended
	Mar. 31, 2019 USD ($) $ / € ¥ / $ $ / R$	Dec. 31, 2018 USD ($) $ / € ¥ / $ $ / R$
USD/Brazilian Real
Derivative [Line Items]
Notional value	$ 1,000,000	$ 1,000,000.0
Forward rate	3.8757	3.8651
Unrealized gain/(loss) recorded at balance sheet date	$ 10,000	$ 5,000
USD/Euro
Derivative [Line Items]
Notional value	$ 22,000,000	$ 20,000,000.0
Forward rate	1.1331	1.1421
Unrealized gain/(loss) recorded at balance sheet date	$ 181,000	$ (97,000)
USD/Chinese Yuan Renminbi
Derivative [Line Items]
Notional value	$ 28,000,000
Forward rate | $ / R$	6.7365
Unrealized gain/(loss) recorded at balance sheet date	$ (59,000)
USD/Chinese Yuan Renminbi | USD/Chinese Yuan Renminbi
Derivative [Line Items]
Notional value		$ 27,000,000
Forward rate | ¥ / $		6.8969
Unrealized gain/(loss) recorded at balance sheet date		$ (116,000)
USD/Chinese Yuan Renminbi | USD/Chinese Yuan Renminbi
Derivative [Line Items]
Notional value		$ 5,000,000
Forward rate | ¥ / $		6.9245
Unrealized gain/(loss) recorded at balance sheet date		$ (41,000)