Comprehensive Income (AOCI Rollforward) (Details) - USD ($)		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	[1]	$ (1,130,836)
Comprehensive Income		79,518,748	$ 74,674,373
Balance at end of period		(1,892,082)	8,803,947
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		(44,909)	1,403,899
Other Comprehensive (loss) income before reclassifications		324,844	(942,974)
Comprehensive Income		324,844	(942,974)
Balance at end of period		279,935	460,925
Unrealized gains on available-for-sale securities:
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		829,907	10,868,322
Other Comprehensive (loss) income before reclassifications		(508,348)	(2,073,471)
Amounts reclassified from accumulated other comprehensive income		300,771	1,697,976
Comprehensive Income		(207,577)	(375,495)
Balance at end of period		622,330	10,492,827
Unrealized gains (losses) on derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period		(1,915,834)	(959,206)
Other Comprehensive (loss) income before reclassifications		(1,237,475)	(1,190,599)
Amounts reclassified from accumulated other comprehensive income		358,962	0
Comprehensive Income		(878,513)	(1,190,599)
Balance at end of period		$ (2,794,347)	$ (2,149,805)

[1] Note: The condensed consolidated balance sheet at December 31, 2015 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.