Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
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Fixed interest rate related to the interest rate derivative.

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The net gain (loss) during the reporting period due to ineffectiveness in foreign currency cash flow hedges. Recognized in earnings.

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-SubTopic 10
-Section 50
-Paragraph 4C
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Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of foreign currency derivatives not designated as hedging instruments.

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The net gain (loss) during the reporting period due to ineffectiveness in interest rate cash flow hedges. Recognized in earnings.

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Financial Instruments Financial Instruments Textual (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months			$ 2,700
Designated as Hedging Instrument [Member] \| Cross Currency Swap [Member]
Derivative [Line Items]
Line Of Credit Facility Forecasted Borrowing Amount	$ 100,000		$ 100,000
Derivative, Fixed Interest Rate	0.01%		0.01%
Gain (Loss) on Foreign Currency Cash Flow Hedge Ineffectiveness	$ 0		$ 0
Designated as Hedging Instrument [Member] \| 2.52% $50 Million Interest Rate Swap [Member]
Derivative [Line Items]
Line Of Credit Facility Forecasted Borrowing Amount	$ 50,000		$ 50,000
Derivative, Fixed Interest Rate	2.52%		2.52%
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness	$ 0		$ 0
Designated as Hedging Instrument [Member] \| 2.25% $100 Million Interest Rate Swap [Member]
Derivative [Line Items]
Line Of Credit Facility Forecasted Borrowing Amount	$ 100,000		$ 100,000
Derivative, Fixed Interest Rate	2.25%		2.25%
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness	$ 0		$ 0
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	452,100		452,100		$ 394,800
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	$ (4,400)	$ 4,500	$ (200)	$ 6,300