Variable Interest Entities Text Tag (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2010	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2010	Mar. 31, 2007	Mar. 31, 2017	Dec. 30, 2010	Mar. 31, 2008
Entity Information [Line Items]
Variable Interest Entity, Funded Exposure, Debt Investment						$ 13,000
Variable Interest Entity, Funded Exposure, Equity Invesment						407
% of Carver Statutory Trust I owned		100.00%
Variable Interest Entity, Rights Transferred						90,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount						35,100
New Markets Tax Credit Award			$ 25,000	$ 65,000	$ 59,000
Proceeds from transfer of equity interest in VIEs	$ 6,700
Carver Statutory Trust 1
Entity Information [Line Items]
Variable Interest Entity, Funded Exposure, Debt Investment		$ 13,000				13,000
Variable Interest Entity, Funded Exposure, Equity Invesment		$ 400				400
Variable Interest Entity, Rights Transferred						0
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount						$ 0
CDE 10
Entity Information [Line Items]
Variable Interest Entity, Rights Transferred								$ 19,000
CDE 1-9, CDE 11-12
Entity Information [Line Items]
Variable Interest Entity, Rights Transferred								$ 40,000
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount							$ 7,800