Document and Entity Information Document - USD ($)	12 Months Ended
	Mar. 31, 2019	Sep. 30, 2018
Entity Information [Line Items]
Entity Registrant Name	CARVER BANCORP INC
Entity Central Index Key	0001016178
Current Fiscal Year End Date	--03-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-K
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding	3,697,914
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Shell Company	false
Entity Smaller Reporting Company	true
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Public Float		$ 15,941,759