Quarterly Financial Data (Unaudited) (Details) - USD ($) |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2017 |
Sep. 30, 2017 |
Jun. 30, 2017 |
Mar. 31, 2017 |
Dec. 31, 2016 |
Sep. 30, 2016 |
Jun. 30, 2016 |
Mar. 31, 2016 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Quarterly Financial Information Disclosure [Abstract] | |||||||||||
| Revenue | $ 547,717,714 | $ 509,530,511 | $ 470,085,693 | $ 415,752,274 | $ 406,852,800 | $ 460,191,903 | $ 443,829,924 | $ 405,277,532 | $ 1,943,086,192 | $ 1,716,152,159 | $ 1,512,298,686 |
| Operating income (loss) | 10,131,691 | 6,292,598 | 3,438,503 | (777,320) | (1,283,597) | 6,026,809 | 7,046,310 | 3,820,994 | 19,085,472 | 15,610,516 | 22,906,524 |
| Net income (loss) | $ 13,348,956 | $ 2,391,682 | $ (245,366) | $ (2,872,043) | $ (2,965,752) | $ 2,362,050 | $ 1,930,769 | $ 262,611 | $ 12,623,229 | $ 1,589,678 | $ 7,845,674 |
| Earnings (Loss) per common share: | |||||||||||
| Basic (USD per share) | $ 0.49 | $ 0.09 | $ (0.01) | $ (0.10) | $ (0.10) | $ 0.08 | $ 0.07 | $ 0.01 | $ 0.46 | $ 0.06 | $ 0.29 |
| Diluted (USD per share) | $ 0.48 | $ 0.09 | $ (0.01) | $ (0.10) | $ (0.10) | $ 0.08 | $ 0.07 | $ 0.01 | $ 0.45 | $ 0.05 | $ 0.28 |
| Remeasurement of net deferred tax liability resulting from the TCJA | $ (8,944,734) | $ 0 | $ 0 | ||||||||