Consolidated Statements of Stockholders' Equity - USD ($) |
Total |
Additional Paid-In Capital [Member] |
Accumulated Other Comprehensive (Loss) Income [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 (stock compensation plans) | 422,610 | 422,318 | $ 292 | ||||
| Issuance of common stock (stock compensation plans), shares | 29,162 | ||||||
| Share-based compensation | 1,024,650 | 1,024,328 | $ 322 | ||||
| Share-based compensation, shares | 32,176 | ||||||
| Net income (loss) | (18,178,078) | (18,178,078) | |||||
| Cash dividends declared | (8,587) | (8,587) | |||||
| Grant of stock options | 187,444 | (187,444) | |||||
| Reclassification of equity unrealized gains | (4,918,655) | 4,918,655 | |||||
| Other comprehensive income (loss) | (6,602,985) | (6,602,985) | |||||
| Ending balance at Mar. 31, 2018 | 425,353,714 | 257,035,648 | (14,205,915) | 223,437,587 | (41,226,357) | $ 256,259 | $ 56,492 |
| Ending balance, shares at Mar. 31, 2018 | 25,625,819 | 5,649,240 | |||||
| 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 | |||||
| Net income (loss) | (17,761,577) | ||||||
| Other comprehensive income (loss) | (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 | |||||
| Beginning balance at Mar. 31, 2018 | 425,353,714 | 257,035,648 | (14,205,915) | 223,437,587 | (41,226,357) | $ 256,259 | $ 56,492 |
| Beginning balance, shares at Mar. 31, 2018 | 25,625,819 | 5,649,240 | |||||
| Issuance of common stock (stock compensation plans) | 960,773 | 960,139 | $ 634 | ||||
| Issuance of common stock (stock compensation plans), shares | 63,430 | ||||||
| Share-based compensation | 536,472 | 536,472 | |||||
| Net income (loss) | (789,855) | (789,855) | |||||
| Cash dividends declared | (3,930,019) | (3,930,019) | |||||
| Grant of stock options | 133,656 | (133,656) | |||||
| Other comprehensive income (loss) | (2,461,046) | (2,461,046) | |||||
| Ending balance at Jun. 30, 2018 | 419,670,039 | 258,665,915 | (16,666,961) | 218,584,057 | (41,226,357) | $ 256,893 | $ 56,492 |
| Ending balance, shares at Jun. 30, 2018 | 25,689,249 | 5,649,240 | |||||
| Issuance of common stock (stock compensation plans) | 321,627 | 321,349 | $ 278 | ||||
| Issuance of common stock (stock compensation plans), shares | 27,802 | ||||||
| Share-based compensation | 553,090 | 552,928 | $ 162 | ||||
| Share-based compensation, shares | 16,168 | ||||||
| Net income (loss) | 1,206,356 | 1,206,356 | |||||
| Cash dividends declared | (3,934,135) | (3,934,135) | |||||
| Grant of stock options | 126,870 | (126,870) | |||||
| Other comprehensive income (loss) | (2,276,950) | (2,276,949) | |||||
| 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 | |||||
| Beginning balance at Dec. 31, 2018 | 398,869,901 | 261,258,423 | (14,228,059) | 192,751,208 | (41,226,357) | $ 258,194 | $ 56,492 |
| Beginning balance, shares at Dec. 31, 2018 | 25,819,341 | 5,649,240 | |||||
| Issuance of common stock (stock compensation plans) | 404,055 | 403,722 | $ 333 | ||||
| Issuance of common stock (stock compensation plans), shares | 33,334 | ||||||
| Share-based compensation | 442,920 | 442,920 | |||||
| Net income (loss) | 23,023,164 | 23,023,164 | |||||
| Cash dividends declared | (4,752) | (4,752) | |||||
| Grant of stock options | 144,226 | (144,226) | |||||
| Other comprehensive income (loss) | 6,468,473 | 6,468,473 | |||||
| Ending balance at Mar. 31, 2019 | 429,203,761 | 262,249,291 | (7,759,586) | 215,625,394 | (41,226,357) | $ 258,527 | $ 56,492 |
| Ending balance, shares at Mar. 31, 2019 | 25,852,675 | 5,649,240 | |||||
| Beginning balance at Dec. 31, 2018 | 398,869,901 | 261,258,423 | (14,228,059) | 192,751,208 | (41,226,357) | $ 258,194 | $ 56,492 |
| Beginning balance, shares at Dec. 31, 2018 | 25,819,341 | 5,649,240 | |||||
| Net income (loss) | 32,997,997 | ||||||
| Other comprehensive income (loss) | 14,646,453 | ||||||
| Ending balance at Sep. 30, 2019 | 442,551,605 | 265,680,180 | 418,394 | 217,362,373 | (41,226,357) | $ 260,523 | $ 56,492 |
| Ending balance, shares at Sep. 30, 2019 | 26,052,220 | 5,649,240 | |||||
| Beginning balance at Mar. 31, 2019 | 429,203,761 | 262,249,291 | (7,759,586) | 215,625,394 | (41,226,357) | $ 258,527 | $ 56,492 |
| Beginning balance, shares at Mar. 31, 2019 | 25,852,675 | 5,649,240 | |||||
| Issuance of common stock (stock compensation plans) | 752,914 | 752,354 | $ 560 | ||||
| Issuance of common stock (stock compensation plans), shares | 55,933 | ||||||
| Share-based compensation | 1,218,804 | 1,218,195 | $ 609 | ||||
| Share-based compensation, shares | 60,969 | ||||||
| Net income (loss) | 4,788,454 | 4,788,454 | |||||
| Cash dividends declared | (4,032,416) | (4,032,416) | |||||
| Grant of stock options | 100,485 | (100,485) | |||||
| Other comprehensive income (loss) | 5,922,207 | 5,922,207 | |||||
| Ending balance at Jun. 30, 2019 | 437,853,724 | 264,320,325 | (1,837,379) | 216,280,947 | (41,226,357) | $ 259,696 | $ 56,492 |
| Ending balance, shares at Jun. 30, 2019 | 25,969,577 | 5,649,240 | |||||
| Issuance of common stock (stock compensation plans) | 280,614 | 280,385 | $ 229 | ||||
| Issuance of common stock (stock compensation plans), shares | 22,926 | ||||||
| Share-based compensation | 1,020,616 | 1,020,018 | $ 598 | ||||
| Share-based compensation, shares | 59,717 | ||||||
| Net income (loss) | 5,186,379 | 5,186,379 | |||||
| Cash dividends declared | (4,045,501) | (4,045,501) | |||||
| Grant of stock options | 59,452 | (59,452) | |||||
| Other comprehensive income (loss) | 2,255,773 | 2,255,773 | |||||
| Ending balance at Sep. 30, 2019 | $ 442,551,605 | $ 265,680,180 | $ 418,394 | $ 217,362,373 | $ (41,226,357) | $ 260,523 | $ 56,492 |
| Ending balance, shares at Sep. 30, 2019 | 26,052,220 | 5,649,240 |