Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)		3 Months Ended			6 Months Ended		12 Months Ended
	Apr. 02, 2018	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Aug. 31, 2019	Mar. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Interest-bearing funds deposited in other banks		$ 2,500,000			$ 2,500,000
Non-marketable securities		10,389,000			10,389,000		$ 10,079,000
Investment securities Amortized to interest income		79,000		$ 13,000	134,000	$ 25,000
Net loan origination costs					20,076,000		17,839,000
Net amortization to income		1,587,000		1,238,000	2,891,000	2,389,000
Premiums in loan portfolio		54,785,000			$ 54,785,000		60,413,000
Percentage of write down of loan balance					40.00%
Loans pledged as collateral		23,303,000			$ 23,303,000		28,833,000
Principal portion of loans serviced, fair value		108,195,000			108,195,000		113,581,000
Bank's reserves against future losses	$ 17,351,000
General reserve benefit					$ 11,555,000
Increase in general reserve balance as result of COVID-19		6,768,000
Intangible assets useful life					20 years
Goodwill		150,803,000		150,803,000	$ 150,803,000	150,803,000	150,803,000
Intangible assets, net		51,814,000		53,259,000	51,814,000	53,259,000	52,536,000
Amortization of intangible assets		361,000		362,000	722,000	723,000
Financing receivable, recorded investment, 90 days past due and still accruing		45,000			45,000		0
Depreciation and amortization		139,000		105,000	261,000	205,000
Amortization expense		586,000		597,000	1,308,000	1,118,000
Deferred costs		4,709,000		5,584,000	$ 4,709,000	$ 5,584,000	$ 5,105,000
Potential dilutive common shares excluded from EPS computation					851,272	498,714
Stock based compensation award					335,773	375,481
Stock based compensation award, Amount		$ 520,000		$ 340,000	$ 987,000	$ 505,000
Stock based compensation award per diluted common share		$ 0.02		$ 0.01	$ 0.04	$ 0.02
Unrecognized compensation cost related to unvested stock options and restricted stock		$ 2,845,000			$ 2,845,000
Unrecognized compensation cost related to unvested stock options and restricted stock, recognition period					45 months
Tier 1 leverage capital ratio		16.96%			16.96%
Capital conversation buffer					2.50%		2.50%
Restricted Shares [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stock based compensation award			165,674		165,674	167,849	216,148
Restricted Stock Units [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stock based compensation award					0	0	26,040
Medallion Bank [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reserves against future losses					$ 2,025,000
Amortization of intangible assets							$ 0
Additional impairment of goodwill					0
RPAC [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Premiums in loan portfolio	$ 12,387,000
Financing receivable, recorded investment, 90 days past due and still accruing		$ 5,251,000		$ 6,875,000	5,251,000	$ 6,875,000	5,758,000
Loan portfolio premium amortized to interest income		179,000		$ 1,081,000	508,000	$ 2,173,000
Additional impairment of intangible assets					0
91+ [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Premiums in loan portfolio		15,576,000			15,576,000		8,663,000
91+ [Member] | Loans [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Premiums in loan portfolio		$ 15,576,000			$ 15,576,000		$ 8,663,000
Total loans more than 90 days past due ,percentage		1.26%			1.26%		0.76%
91+ [Member] | Loans [Member] | CARES Act [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Premiums in loan portfolio		$ 115,216,000			$ 115,216,000
Total loans more than 90 days past due ,percentage		9.30%			9.30%
Bank Holding Company Accounting [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net premium on investment securities					$ 271,000		$ 248,000
Private Placement [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Interest reserve								$ 2,970,000	$ 2,970,000
Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Interest bearing loan term					4 years
Estimated useful life of fixed assets					3 years
Tier 1 leverage capital to total assets ratio		15.00%			15.00%
Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Interest bearing loan term					7 years
Estimated useful life of fixed assets					10 years