Quarterly Information (Unaudited) (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
Selected Quarterly Financial Information [Abstract]
Total revenues	$ 156,997,000	$ 137,639,000	$ 127,116,000	$ 122,790,000	$ 141,399,000	$ 125,704,000	$ 118,929,000	$ 116,638,000	$ 544,542,925	$ 502,668,332	$ 490,821,420
Provision for loan losses	28,533,000	48,944,000	40,359,000	30,591,000	16,631,000	40,456,000	32,824,000	27,710,000	148,426,578	117,620,140	119,095,712
General and Administrative Expense	78,626,000	76,964,000	64,936,000	67,777,000	75,282,000	64,850,000	62,767,000	66,208,000	288,303,715	269,107,669	244,273,626
Interest expense	4,914,000	4,637,000	4,158,000	4,225,000	5,052,000	5,001,000	4,791,000	4,247,000	17,934,060	19,089,635	21,504,208
Income tax expense	6,984,000	834,000	3,604,000	4,559,000	18,778,000	15,204,000	6,511,000	7,265,000	15,981,057	47,757,808	38,157,492
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0	0	479,000	(37,141,000)	3,487,000	1,487,000	(2,236,000)	1,859,000	(36,662,381)	4,596,938	5,809,912
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
Earnings per share:
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