Quarterly Information (Unaudited) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Selected Quarterly Financial Information [Abstract]
Total revenues	$ 146,280,000	$ 130,946,000	$ 124,441,000	$ 123,867,000	$ 163,018,000	$ 146,996,000	$ 141,573,000	$ 138,441,000	$ 525,533,267	$ 590,029,015	$ 544,542,925
Provision for credit losses	5,636,000	28,857,000	26,090,000	25,661,000	32,252,000	55,219,000	52,968,000	41,291,000	86,244,714	181,730,182	148,426,578
General and administrative expenses	77,411,000	77,875,000	75,293,000	71,608,000	96,707,000	90,558,000	78,452,000	81,776,000	302,186,290	347,493,260	288,303,715
Interest expense	6,940,000	7,305,000	5,893,000	5,562,000	8,035,000	7,130,000	6,328,000	4,403,000	25,698,836	25,896,130	17,934,060
Income tax expense	11,409,000	2,418,000	3,767,000	5,527,000	2,721,000	356,000	1,312,000	2,363,000	23,120,599	6,751,965	15,981,057
Income (loss) from discontinued operations									0	0	(36,662,381)
Net income	$ 44,884,000	$ 14,491,000	$ 13,398,000	$ 15,509,000	$ 23,303,000	$ (6,267,000)	$ 2,513,000	$ 8,608,000	$ 88,282,828	$ 28,157,478	$ 37,235,134
Earnings per share:
Basic (in dollars per share)	$ 7.25	$ 2.32	$ 2.01	$ 2.26	$ 3.23	$ (0.87)	$ 0.32	$ 1.01	$ 13.59	$ 3.66	$ 4.14
Diluted (in dollars per share)	$ 6.96	$ 2.25	$ 1.96	$ 2.24	$ 3.18	$ (0.87)	$ 0.31	$ 0.97	$ 13.23	$ 3.54	$ 4.05