Consolidated Statements of Other Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	[1]
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss) after taxes/net decrease on net assets resulting from operations	$ (26,907)	$ 1,996	$ (22,739)
Other comprehensive income (loss), net of tax	1,013	1,081	(82)
Total comprehensive income (loss)	(25,894)	3,077	(22,821)
Less: comprehensive income attributable to the non-controlling interest	7,876	3,758	2,307
Total comprehensive loss attributable to Medallion Financial Corp.	$ (33,770)	$ (681)	$ (25,128)

[1] Balance includes the nine months ended December 31, 2018 under Bank Holding Company Accounting and the three months ended March 31, 2018 under Investment Company Accounting.