Derivatives - Forward Notional Contracts (Details) - Jun. 30, 2018 - Foreign currency forward contracts € in Thousands, ₩ in Thousands, ¥ in Thousands, ¥ in Thousands, £ in Thousands, kr in Thousands, kr in Thousands, SFr in Thousands, R$ in Thousands, $ in Thousands, $ in Thousands, $ in Thousands, $ in Thousands, $ in Thousands	CHF (SFr)	DKK (kr)	MXN ($)	CNY (¥)	KRW (₩)	GBP (£)	CAD ($)	JPY (¥)	SGD ($)	EUR (€)	HKD ($)	SEK (kr)	AUD ($)	BRL (R$)
Designated as hedging instrument | Derivatives designated as cash flow hedges
Derivative [Line Items]
Notional amount of derivative	SFr 1,158	kr 11,650	$ 94,275	¥ 66,000		£ 2,975	$ 2,410			€ 12,870		kr 13,830
Not designated as hedging instrument
Derivative [Line Items]
Notional amount of derivative	SFr 255	kr 2,885	$ 18,700	¥ 95,228	₩ 2,700,000	£ 1,584	$ 3,098	¥ 260,000	$ 6,900	€ 25,861	$ 11,000	kr 10,536	$ 8,400	R$ 8,500