Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 111,248,743	$ 97,556,741
Other comprehensive income (loss) before tax:
Foreign currency translation adjustments	1,626,178	188,590
Unrealized gains on derivatives	67,047	641,975
Unrealized gains (losses) on debt securities, net	(21,280)	2,170,254
Other comprehensive income, before tax	1,671,945	3,000,819
Expense for income taxes related to components of other comprehensive income	9,611	984,280
Other comprehensive income, net of tax	1,662,334	2,016,539
Comprehensive Income	$ 112,911,077	$ 99,573,280