Borrowing Facilities (Schedule of Long-Term Debt Principal versus Amortization Costs) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Debt Instrument Carrying Amount	$ 156,147	$ 214,172
Unamortized Debt Issuance Expense	2,077	$ 2,492
Medium Term Notes Due 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount	150,000
Unamortized Debt Issuance Expense	2,077
Capital Lease Obligations Due 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount	6,147
Unamortized Debt Issuance Expense	$ 0

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant