Derivatives - Effect of Derivative Instruments on Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Effect of derivative instruments on results of operations
Pre-tax Gain Recognized in Other Comprehensive Income (Loss) on Derivatives	$ 4,696	$ 699
Interest expense
Effect of derivative instruments on results of operations
Pre-tax Loss Reclassified from Accumulated Other Comprehensive Income (Loss) into Income (Loss)	$ (474)	$ (1,013)

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

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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