Related Parties (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Payments to Acquire Property, Plant, and Equipment	$ 43,658,000	$ 23,841,000	$ 34,969,000
Tower Property [Member]
Percentage of stock owned	64.00%
Related parties owned common stock	233,796
Amount borrowed and repaid under line of credit	3,000,000	2,000,000	5,000,000
Line of Credit, Current	1,300,000
Line of credit, amount outstanding	13,500,000	0	0
Line of credit interest received	15,000	12,000	51,000
Letters of Credit Outstanding, Amount	0	0	0
Line of Credit Facility, Commitment Fee Amount	0	0	0
Long-term Construction Loan	0	0	0
Rent paid to the Company	69,000	67,000	66,000
Rent per square foot	15.17	14.92	15.08
Chief Executive Officer [Member]
State tax credits sold	396,000	846,000	465,000
Former Chief Executive Officer [Member]
State tax credits sold		282,000
Vice Chairman [Member]
State tax credits sold	155,000	456,000
President [Member]
State tax credits sold	60,000
Director [Member]
State tax credits sold		200,000
Parking Lots [Member]
Payments to Acquire Property, Plant, and Equipment			$ 7,100,000