Derivatives Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Derivative [Line Items]
Convertible Debt 2022 Conversion Feature, Initial Fair Value	$ 28,859,000		$ 28,859,000
Proceeds from Issuance of Warrants			14,100,000	$ 12,376,000
Foreign currency forward contracts
Derivative [Line Items]
Notional amount of derivatives, matured during period	45,421,000	$ 59,663,000	126,456,000	171,889,000
Selling, General and Administrative Expenses | Foreign currency forward contracts
Derivative [Line Items]
Gain recognized in income		271,000	$ 64,000
Loss on derivative	(53,000)			(106,000)
Minimum
Derivative [Line Items]
Derivative, percentage of forcasted transactions with currency rate exposure			50.00%
Maximum
Derivative [Line Items]
Derivative, percentage of forcasted transactions with currency rate exposure			90.00%
Cash Flow Hedging [Member]
Derivative [Line Items]
Gain (Loss)	(438,000)	798,000	$ 200,000	1,250,000
Cash Flow Hedging [Member] | Sales [Member]
Derivative [Line Items]
Gain recognized in income	399,000	1,417,000	165,000	2,826,000
Cash Flow Hedging [Member] | Cost of Sales [Member]
Derivative [Line Items]
Gain recognized in income			35,000
Loss on derivative	(837,000)	$ (619,000)		(1,576,000)
Convertible Subordinated Debt | Convertible Senior Notes at 5.00% February 2021 [Member]
Derivative [Line Items]
Convertible due 2021 - Bond Hedge, Initial Fair Value	27,975,000		27,975,000
Convertible Debt Conversion Feature, Initial Fair Value	(34,480,000)		(34,480,000)
Debt Instrument, Face Amount	$ 150,000,000		$ 150,000,000		$ 150,000,000
Interest rate (as a percent)	5.00%		5.00%
Convertible Subordinated Debt | Convertible Senior Notes at 4.50% February 2022 [Domain]
Derivative [Line Items]
Proceeds from Issuance of Warrants			$ 14,100,000	$ 14,100,000
Convertible due 2022 - Bond Hedge, Fair Value at Issuance	$ 24,780,000		24,780,000
Debt Instrument, Face Amount	$ 120,000,000		$ 120,000,000
Interest rate (as a percent)	4.50%		4.50%