Consolidated Statement of Stockholders' Equity - 9 months ended Sep. 30, 2018 - USD ($)	Total	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Class A Common Stock [Member]	Class B Common Stock [Member]
Beginning balance at Dec. 31, 2017	$ 448,696,104	$ 255,401,558	$ (2,684,275)	$ 236,893,041	$ (41,226,357)	$ 255,645	$ 56,492
Beginning balance, shares at Dec. 31, 2017						25,564,481	5,649,240
Issuance of common stock	1,705,010	1,703,806				$ 1,204
Issuance of common stock, shares						120,394
Share-based compensation	2,114,212	2,113,728				$ 484
Share-based compensation, shares						48,344
Net (loss) income	(17,761,577)			(17,761,577)
Cash dividends declared	(7,872,741)			(7,872,741)
Grant of stock options		447,970		(447,970)
Reclassification of equity unrealized gains			(4,918,655)	4,918,655
Other comprehensive (loss) income	(11,340,980)		(11,340,980)
Ending balance at Sep. 30, 2018	$ 415,540,028	$ 259,667,062	$ (18,943,910)	$ 215,729,408	$ (41,226,357)	$ 257,333	$ 56,492
Ending balance, shares at Sep. 30, 2018						25,733,219	5,649,240