Comprehensive Income (Reclassification Out of Accumulated Other Comprehensive Income) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Provision for Income Taxes	$ (145,121,597)	$ (126,721,911)	$ (105,134,094)
Amounts Reclassified from Other Comprehensive Income
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period	3,822,086	10,135,535	11,784,182
Amounts Reclassified from Other Comprehensive Income | Unrealized gains and (losses) on available-for-sale securities
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Realized gain (loss) on sale of securities	6,960,881	15,593,131	18,129,511
Provision for Income Taxes	(2,436,308)	(5,457,596)	(6,345,329)
Total reclassifications for the period	4,524,573	10,135,535	11,784,182
Amounts Reclassified from Other Comprehensive Income | Unrealized gains (losses) on derivatives
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Realized gain (loss) on sale of securities	(1,080,750)	0	0
Provision for Income Taxes	378,263	0	0
Total reclassifications for the period	$ (702,487)	$ 0	$ 0