Comprehensive Income (Reclassification Out of Accumulated Other Comprehensive Income) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Provision for Income Taxes	$ (20,323,345)		$ (22,442,739)
Amounts Reclassified from Other Comprehensive Income [Member] | Unrealized gains(losses) on available-for-sale securities [Member]
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Realized gain (loss) on sale of securities	2,822,207	[1]	1,494,565	[1]
Provision for Income Taxes	(987,772)	[1]	(523,098)	[1]
Total reclassifications for the period	$ 1,834,435	[1]	$ 971,467	[1]

[1] Amounts in parentheses indicate debits.