Derivatives (Classification on the Consolidated Statements of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Earnings from equity method investments \| Interest rate swaps \| Designated as hedge
Derivative financial instruments on consolidated statements of operations
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)	$ 2,351	$ 78
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Earnings (Effective Portion)	$ (9)	(87)
Earnings from equity method investments \| Interest rate cap \| Designated as hedge
Derivative financial instruments on consolidated statements of operations
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)		(5)
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Earnings (Effective Portion)		(5)
Earnings from equity method investments \| Foreign exchange contracts \| Designated as hedge
Derivative financial instruments on consolidated statements of operations
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)		(299)
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Earnings (Effective Portion)		0
Interest Expense \| Interest rate swaps \| Designated as hedge
Derivative financial instruments on consolidated statements of operations
Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion)		467
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Earnings (Effective Portion)		(30)
Other Expense \| Interest rate cap \| Not designated as hedge
Derivative financial instruments on consolidated statements of operations
Amount of Gain (Loss) Recognized in Income For the Three Months Ended March 31, 2017		47
Other Expense \| Foreign exchange contracts \| Not designated as hedge
Derivative financial instruments on consolidated statements of operations
Amount of Gain (Loss) Recognized in Income For the Three Months Ended March 31, 2017		$ (125)

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a),(c),(d),(e)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

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The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624177-113959

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The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

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