Comprehensive Income (AOCI Rollforward) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	$ 17,570,711	$ 12,542,203
Comprehensive Income	227,334,601	173,615,348	154,893,528
Balance at end of period	21,975,363	17,570,711	12,542,203
Foreign currency translation adjustments:
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	2,458,933	2,129,957	566,903
Other Comprehensive income before reclassifications	48,989	328,976	1,563,054
Amounts reclassified from accumulated other comprehensive income	0	0	0
Comprehensive Income	48,989	328,976	1,563,054
Balance at end of period	2,507,922	2,458,933	2,129,957
Unrealized gains(losses) on available-for-sale securities:
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	15,111,778	10,412,246	21,750,000
Other Comprehensive income before reclassifications	16,139,845	10,138,902	(7,012,974)
Amounts reclassified from accumulated other comprehensive income	(11,784,182)	(5,439,370)	(4,324,780)
Comprehensive Income	4,355,663	4,699,532	(11,337,754)
Balance at end of period	$ 19,467,441	$ 15,111,778	$ 10,412,246