Income Tax Expense Components of Federal and State Income Tax Provision (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Expense [Abstract]
Current Federal Tax Expense (Benefit)	$ 4,747	$ 5,002	$ 3,902
Current State and Local Tax Expense (Benefit)	511	428	338
Current Income Tax Expense (Benefit)	5,258	5,430	4,240
Deferred Federal - Investment Tax Credit	(71)	(63)	(61)
Deferred Federal - Deferred Revenue	(77)	(75)	(75)
Deferred Federal - Land Donations	29	392	201
Deferred Federal - Depreciation	2,411	1,990	1,909
Deferred Federal - Other	(184)	(7)	5
Deferred Federal Income Tax Expense (Benefit)	2,108	2,237	1,979
Deferred State - Land Donations	(83)	0	0
Deferred State - Other	48	9	(354)
Deferred State and Local Income Tax Expense (Benefit)	(35)	9	(354)
Deferred Income Tax Expense (Benefit)	2,073	2,246	1,625
Total Income Tax Expense	$ 7,331	$ 7,676	$ 5,865