Comprehensive Income (Reclassification Out of Accumulated Other Comprehensive Income) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Provision for Income Taxes	$ (37,715,317)	$ (31,655,724)	$ (104,841,502)	$ (93,677,000)
Amounts Reclassified from Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period	1,037,510	1,506,238	3,980,720	9,023,968
Amounts Reclassified from Other Comprehensive Income | Unrealized gains on available-for-sale securities:
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Realized gain on sale of securities	2,033,819	2,317,289	6,561,834	13,883,028
Provision for Income Taxes	(711,837)	(811,051)	(2,296,642)	(4,859,060)
Total reclassifications for the period	1,321,982	1,506,238	4,265,192	9,023,968
Amounts Reclassified from Other Comprehensive Income | Unrealized gains (losses) on derivatives
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Realized gain on sale of securities	(437,650)	0	(437,650)	0
Provision for Income Taxes	153,178	0	153,178	0
Total reclassifications for the period	$ (284,472)	$ 0	$ (284,472)	$ 0