Accumulated Other Comprehensive Income (Schedule Of Changes In Balances Of Each Component Of Accumulated Other Comprehensive Income, Net Of Tax) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	$ 8,818,430	$ 7,509,165
Other comprehensive income before reclassifications	1,570,244	1,304,483
Amounts reclassified from accumulated other comprehensive income	(10,694)	(125,163)
Net current-period other comprehensive income	1,559,550	1,179,320
Ending balance	10,377,980	8,688,485
Unrealized Gains And Losses On Available-For-Sale Securities [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	8,920,883	7,563,541
Other comprehensive income before reclassifications	1,570,244	1,304,483
Amounts reclassified from accumulated other comprehensive income	(11,482)	(126,825)
Net current-period other comprehensive income	1,558,762	1,177,658
Ending balance	10,479,645	8,741,199
Postretirement Benefits Plans [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(102,453)	(54,376)
Other comprehensive income before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income	788	1,662
Net current-period other comprehensive income	788	1,662
Ending balance	$ (101,665)	$ (52,714)