Property and Equipment (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property and equipment
Property and equipment, gross	$ 42,691,000	$ 41,680,000
Less: accumulated depreciation	(19,581,000)	(16,080,000)
Property and equipment, net excluding construction and equipment installations in progress	23,110,000	25,600,000
Property and equipment, net	24,675,000	26,861,000
Depreciation expense	3,800,000	3,500,000	3,200,000
Land and improvements
Property and equipment
Property and equipment, gross	8,724,000	8,724,000
Building
Property and equipment
Property and equipment, gross	6,827,000	6,734,000
Equipment
Property and equipment
Property and equipment, gross	21,880,000	21,105,000
Towers
Property and equipment
Property and equipment, gross	5,260,000	5,117,000
Equipment installations in progress
Property and equipment
Property and equipment, net	$ 1,565,000	$ 1,261,000