Long-Term Debt And Credit Facilities (Revolving Line Of Credit) (Narrative) (Details) (Revolving Credit Facility [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 10.0
Debt maturity date	Mar. 31, 2018
Tangible net worth requirement	(21.5)	(24.5)	(24.5)	(23.5)	(23.5)	(23.5)	(23.5)	(22.5)	(22.5)	(22.5)	(22.5)	(21.5)	(21.5)
Line of credit facility, amount outstanding	0
Line of credit facility, current borrowing capacity	$ 6.5
Minimum [Member]
Line of Credit Facility [Line Items]
Liquidity ratio	1.50