ACCUMULATED OTHER COMPREHENSIVE INCOME - Components of Accumulated Other Comprehensive Income (Details) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012	Jun. 30, 2013		Jun. 30, 2012
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at December 31, 2012				$ 47,752,375	[1]
Other comprehensive income (loss) before reclassifications				(17,107,369)	[1]
Amounts reclassified from accumulated other comprehensive income				(1,137,419)	[1]
Other comprehensive income (loss)	(23,729,576)		3,895,676	(18,244,788)	[1]	10,555,603
Balance at June 30, 2013	29,507,587	[1]		29,507,587	[1]
Unrealized Gains and (Losses) on Available-for-sale securities
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at December 31, 2012				69,805,305	[1]
Other comprehensive income (loss) before reclassifications				(17,107,369)	[1]
Amounts reclassified from accumulated other comprehensive income				(1,848,032)	[1]
Other comprehensive income (loss)				(18,955,401)	[1]
Balance at June 30, 2013	50,849,904	[1]		50,849,904	[1]
Unrecognized pension and postretirement benefit obligations
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at December 31, 2012				(22,052,930)	[1]
Other comprehensive income (loss) before reclassifications				0	[1]
Amounts reclassified from accumulated other comprehensive income				710,613	[1]
Other comprehensive income (loss)				710,613	[1]
Balance at June 30, 2013	$ (21,342,317)	[1]		$ (21,342,317)	[1]

[1] All amounts are net of tax. Amounts in parentheses indicate debits.