Reclassifications Out Of Accumulated Other Comprehensive Loss (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales, reclassifications	$ 30,584,497	$ 28,538,324	$ 53,849,757	$ 53,349,824
Selling, general and administrative expenses, reclassifications	3,633,683	3,571,349	7,548,124	7,286,299
Gain on sale of equity investments, reclassifications	812,588	152,014	3,881,872	567,544
Less: Income tax expense (benefit)	1,437,000	1,384,000	1,277,000	823,000
Reclassifications, net of tax	1,878,751	3,336,857	(60,468)	1,097,522
Reclassification Out Of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Less: Income tax expense (benefit)	123,000	(352,000)	1,143,000	(184,000)
Reclassifications, net of tax	186,313	(527,415)	1,716,818	(279,885)
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Net Periodic Pension And Postretirement [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of sales, reclassifications	(307,755)	(612,565)	(611,208)	(612,565)
Selling, general and administrative expenses, reclassifications	(195,520)	(418,864)	(410,846)	(418,864)
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Unrealized Net Gains On Available-For-Sale Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of equity investments, reclassifications	$ 812,588	$ 152,014	$ 3,881,872	$ 567,544