Carver Bancorp Inc.-Parent Company Only-Condensed Statements of Financial Condition (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Condensed Balance Sheet Statements, Captions [Line Items]
Other assets	$ 5,853	$ 9,320
Total assets	578,770	563,713
Other liabilities	9,335	14,978
Total liabilities	529,876	516,577
Stockholders’ equity	48,894	47,136	$ 51,971
Total liabilities and equity	578,770	563,713
Parent Company
Condensed Balance Sheet Statements, Captions [Line Items]
Cash on deposit with subsidiaries	496	495	$ 494
Investment in subsidiaries	65,018	62,340
Other assets	161	121
Total assets	65,675	62,956
Borrowings	13,403	13,403
Accounts payable to subsidiaries	739	563
Other liabilities	2,639	1,854
Total liabilities	16,781	15,820
Stockholders’ equity	48,894	47,136
Total liabilities and equity	$ 65,675	$ 62,956