Fair Value Measurements and Derivative Instruments Reporting (Derivative instruments location and fair value amounts) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Interest Rate Swap Asset [Member]
Derivatives, Fair Value [Line Items]
Gross recognized Assets (Liabilities)	$ 315	$ 275
Net Recognized Fair Value Assets (Liabilities)	315	275
Interest Rate Swap - Current [Member] \| Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Gross recognized Assets (Liabilities)	147	77
Net Recognized Fair Value Assets (Liabilities)	147	77
Interest Rate Swap - Non-Current [Member] \| Deposits And Other [Member]
Derivatives, Fair Value [Line Items]
Gross recognized Assets (Liabilities)	168	198
Net Recognized Fair Value Assets (Liabilities)	$ 168	$ 198

Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226003-175313

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Name:	us-gaap_DerivativeAssetFairValueGrossLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant