Debt (Schedule Of Debt Issuance Costs Associated With Long-Term Obligations) (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term Obligations	$ 459,795,331	$ 445,605,998
Unnamortized Debt Issuance Costs	2,734,709	2,715,745
2011 Series A Bonds [Member] | Term Loan Facility [Member]
Debt Instrument [Line Items]
Long-term Obligations	200,333,331	210,999,998
Unnamortized Debt Issuance Costs	1,250,685	1,347,350
2012 Series A Bonds [Member] | Term Loan Facility [Member]
Debt Instrument [Line Items]
Long-term Obligations	183,500,000	194,250,000
Unnamortized Debt Issuance Costs	1,040,988	1,106,275
2017 Series A Bonds [Member] | Term Loan Facility [Member]
Debt Instrument [Line Items]
Long-term Obligations	38,000,000
Unnamortized Debt Issuance Costs	203,643
2016 CoBank Note [Member]
Debt Instrument [Line Items]
Long-term Obligations	41,200,000	43,800,000
2016 CoBank Note [Member] | Term Loan Facility [Member]
Debt Instrument [Line Items]
Long-term Obligations	37,962,000	40,356,000
Unnamortized Debt Issuance Costs	$ 239,393	$ 262,120