Debt (Bank Of America Line Of Credit) (Narrative) (Details)	3 Months Ended	12 Months Ended
Mar. 31, 2018	Dec. 31, 2017
US Bank Of America Line Of Credit [Member]
Debt Instrument [Line Items]
Maturity date	Oct. 31, 2019	Oct. 31, 2019

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration