Comprehensive Income (Reclassification Out of Accumulated Other Comprehensive Income) (Details) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Provision for Income Taxes	$ (25,522,293)		$ (19,808,978)		$ (70,877,180)		$ (62,164,893)
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	6,463,447	[1]	3,343,055	[1]	14,315,778	[1]	7,578,955	[1]
Provision for Income Taxes	(2,262,206)	[1]	(1,170,069)	[1]	(5,010,522)	[1]	(2,652,634)	[1]
Total reclassifications for the period	$ 4,201,241	[1]	$ 2,172,986	[1]	$ 9,305,256	[1]	$ 4,926,321	[1]

[1] Amounts in parentheses indicate debits.