Property, Plant And Equipment (Schedule Of Property, Plant And Equipment) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 77,021	$ 76,397
Less: Accumulated depreciation	64,637	62,560
Property, Plant and Equipment, Net, Total	12,384	13,837
Land, Buildings And Other Support Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	10,818	10,777
Network Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	31,311	31,289
Telephone And Online Plant [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	34,849	34,307
Work In Process [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 43	$ 24