Carver Bancorp Inc.-Parent Company Only Parent Company Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended							12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Interest Expense, Borrowings								$ 1,089	$ 1,154
Other Expenses								8,099	7,735
Income / (loss) before income taxes								249	(844)
Income tax expense (benefit)	$ (31)	$ (62)	$ (57)	$ (16)	$ (8)	$ (16)	$ (72)	166	102	$ 328
Net Income (Loss) Attributable to Carver Bancorp, Inc.								364	(836)
Parent Company [Member]
Income (Loss) from Subsidiaries, before Tax								1,218	14	1,561
Other Income								21	29	35
Total income (loss)								1,239	43	1,596
Interest Expense, Borrowings								446	450	471
Salaries and employee benefits								167	172	181
Shareholder expense								95	82	99
Other Expenses								167	175	183
Total expense								875	879	934
Income / (loss) before income taxes								364	(836)	662
Income tax expense (benefit)								0	0	0
Net Income (Loss) Attributable to Carver Bancorp, Inc.								$ 364	$ (836)	$ 662