Derivative and Hedging Activities Derivative and Hedging Activities - Notional Values (Details) - Foreign Exchange Forward [Member] - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Designated as Hedging Instrument [Member] \| Long [Member]
Derivatives, Fair Value [Line Items]
Purchase	$ 0	$ 12,984
Not Designated as Hedging Instrument [Member] \| Long [Member]
Derivatives, Fair Value [Line Items]
Purchase	4,056	6,942
Not Designated as Hedging Instrument [Member] \| Short [Member]
Derivatives, Fair Value [Line Items]
Sell	$ 11,157	$ 11,332

Nominal or face amount used to calculate payments on the derivative liability.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Notional Amount
-URI http://asc.fasb.org/extlink&oid=6519104

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5579245-113959

Name:	us-gaap_DerivativeLiabilityNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant