Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 97,556,741	$ 80,279,994
Other comprehensive income (loss) before tax:
Foreign currency translation adjustments	188,590	324,844
Unrealized gains (losses) on derivatives	641,975	(1,351,557)
Unrealized gains (losses) on available-for sales securities, net	2,170,254	(319,349)
Other comprehensive income (loss), before tax	3,000,819	(1,346,062)
Expense (Benefit) for income taxes related to components of other comprehensive income (loss)	984,280	(584,816)
Other comprehensive income (loss), net of tax	2,016,539	(761,246)
Comprehensive Income	$ 99,573,280	$ 79,518,748