Derivative Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional amounts of foreign currency forward contracts	$ 129,792	$ 152,984
Swedish Kronor
Derivative [Line Items]
Notional amounts of foreign currency forward contracts	13,701	59,373
Canadian Dollar
Derivative [Line Items]
Notional amounts of foreign currency forward contracts	15,665	7,426
Brazil, Brazil Real
Derivative [Line Items]
Notional amounts of foreign currency forward contracts	8,451	7,794
Australian Dollar
Derivative [Line Items]
Notional amounts of foreign currency forward contracts	1,192	2,817
United Kingdom, Pounds
Derivative [Line Items]
Notional amounts of foreign currency forward contracts	1,037	34,317
Euro
Derivative [Line Items]
Notional amounts of foreign currency forward contracts	78,747	34,800
Japanese Yen
Derivative [Line Items]
Notional amounts of foreign currency forward contracts	727	3,362
Norway, Krone
Derivative [Line Items]
Notional amounts of foreign currency forward contracts	9,486	3,095
Denmark, Kroner
Derivative [Line Items]
Notional amounts of foreign currency forward contracts	$ 786	$ 0