Parent Company Only Condensed Financial Statements - Condensed Statements of Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Condensed Income Statements, Captions [Line Items]
Net interest income (loss)	$ 160,436	$ 127,826	$ 110,811
Provision (benefit) for loan losses	30,059	4,622	69,817
Net interest income (loss) after loss provision	130,377	123,204	40,994
Income (loss) before income taxes	67,850	81,871	(36,981)
Total net income (loss) attributable to Medallion Financial Corp.	43,840	54,108	(34,783)
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Interest and dividend income	24,631	16,446	4,773
Interest expense	11,289	11,209	8,602
Net interest income (loss)	13,342	5,237	(3,829)
Provision (benefit) for loan losses	(353)	(4,718)	5,127
Net interest income (loss) after loss provision	13,695	9,955	(8,956)
Other expense, net	(18,423)	(6,224)	(22,062)
Income (loss) before income taxes	(4,728)	3,731	(31,018)
Income tax benefit	7,940	4,452	10,454
Total net income (loss) attributable to Medallion Financial Corp.	3,212	8,183	(20,564)
Undistributed earnings (losses) of subsidiaries	40,628	45,925	(14,219)
Net income (loss) attributable to parent company	$ 43,840	$ 54,108	$ (34,783)