Consolidated Statements Of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Consolidated Statements Of Comprehensive Income [Abstract]
Net income	$ 3,238,915	$ 2,440,465	$ 8,043,755	$ 5,054,477
Other comprehensive income, before tax:
Amortization related to prior year service cost	2,349	(415)	7,047	9,779
Amortization of unrecognized loss (gain)	171	(1,525)	511	(239)
Unrealized gains (losses) on investments arising during the period	2,142,925	(1,217,304)	3,677,740	543,683
Reclassification adjustment for sale of securities included in net income	(99,790)	49,979	(434,358)	(179,309)
Reclassification adjustment for write-down of securities included in net income	0	150,109	76,539	258,481
Other comprehensive income (loss), before tax	2,045,655	(1,019,156)	3,327,479	632,395
Income tax expense (benefit) related to postretirement health benefits	858	(661)	2,571	3,244
Income tax expense (benefit) related to unrealized gains (losses) on investments arising during the year	737,122	(427,839)	1,273,653	170,908
Income tax (benefit) expense related to reclassification adjustment for sale of securities included in net income	(34,576)	17,377	(155,912)	(61,842)
Income tax expense related to reclassification adjustment for write-down of securities included in net income	0	51,613	26,265	89,888
Net income tax expense (benefit) on other comprehensive income	703,404	(359,510)	1,146,577	202,198
Other comprehensive income (loss)	1,342,251	(659,646)	2,180,902	430,197
Comprehensive income	4,581,166	1,780,819	10,224,657	5,484,674
Less: Comprehensive income attributable to redeemable noncontrolling interest	80,730	0	103,943	0
Comprehensive income attributable to the Company	$ 4,500,436	$ 1,780,819	$ 10,120,714	$ 5,484,674