Earnings Per Share (Details) - USD ($)	3 Months Ended								12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									$ 73,897,515	$ 49,093,080
Income (Loss) from Continuing Operations, Per Diluted Share									$ 8.03	$ 5.48	$ 7.72
Income (Numerator)
Net income	$ 37,940,000	$ 6,260,000	$ 14,538,000	$ (21,503,000)	$ 29,143,000	$ 1,680,000	$ 9,800,000	$ 13,067,000	$ 37,235,134	$ 53,690,018	$ 73,600,294
Shares (Denominator)
Income available to common shareholders (in shares)									8,994,036	8,791,168	8,705,658
Income (Loss) from Continuing Operations, Per Basic Share									$ 8.22	$ 5.58	$ 7.79
Effect of Dilutive Securities Options and restricted stock (in shares)									210,341	167,508	72,386
Diluted (in shares)									9,204,377	8,958,676	8,778,044
Per Share Amount
Basic (in dollars per share)	$ 4.34	$ 0.69	$ 1.60	$ (2.37)	$ 3.25	$ 0.19	$ 1.12	$ 1.50	$ 4.14	$ 6.11	$ 8.45
Diluted (in dollars per share)	$ 4.22	$ 0.67	$ 1.56	$ (2.32)	$ 3.18	$ 0.19	$ 1.10	$ 1.48	$ 4.05	$ 5.99	$ 8.38
Antidilutive options excluded from computation of diluted earnings per share (in shares)									592,947	299,455	733,053
Retained Earnings [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest											$ 67,790,382
Income (Numerator)
Net income									$ 37,235,134	$ 53,690,018	$ 73,600,294