Variable Interest Entities (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2013
Entity Information [Line Items]
Variable Interest Entity, Initial Consolidation, Gain (Loss)	$ 3,250
Variable Interest Entity, Rights Transferred	69,500
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	63,951
Variable Interest Entity, Total Involvment with SPE Asset	63,951
Variable Interest Entity, Funded Exposure, Debt Investment	13,000
Variable Interest Entity, Funded Exposure, Equity Invesment	405
Variable Ineterest Entity, Unfunded Exposure, Funding Commitments	0
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	27,105
Variable Interest Entity, Total Exposure	40,510
Carver Statutory Trust 1
Entity Information [Line Items]
Variable Interest Entity, Initial Consolidation, Gain (Loss)	0
Variable Interest Entity, Rights Transferred	0
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	13,400
Variable Interest Entity, Total Involvment with SPE Asset	13,400
Variable Interest Entity, Funded Exposure, Debt Investment	13,000	$ 13,000
Variable Interest Entity, Funded Exposure, Equity Invesment	400	$ 400
Variable Ineterest Entity, Unfunded Exposure, Funding Commitments	0
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	0
Variable Interest Entity, Total Exposure	13,400
CDE 15, 16, 17
Entity Information [Line Items]
Variable Interest Entity, Initial Consolidation, Gain (Loss)	900
Variable Interest Entity, Rights Transferred	20,500
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	15,564
Variable Interest Entity, Total Involvment with SPE Asset	15,564
Variable Interest Entity, Funded Exposure, Debt Investment	0
Variable Interest Entity, Funded Exposure, Equity Invesment	2
Variable Ineterest Entity, Unfunded Exposure, Funding Commitments	0
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	7,995
Variable Interest Entity, Total Exposure	7,997
CDE 18
Entity Information [Line Items]
Variable Interest Entity, Initial Consolidation, Gain (Loss)	600
Variable Interest Entity, Rights Transferred	13,254
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	0
Variable Interest Entity, Total Involvment with SPE Asset	0
Variable Interest Entity, Funded Exposure, Debt Investment	0
Variable Interest Entity, Funded Exposure, Equity Invesment	0
Variable Ineterest Entity, Unfunded Exposure, Funding Commitments	0
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	5,169
Variable Interest Entity, Total Exposure	5,169
CDE 19
Entity Information [Line Items]
Variable Interest Entity, Initial Consolidation, Gain (Loss)	500
Variable Interest Entity, Rights Transferred	10,746
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	11,033
Variable Interest Entity, Total Involvment with SPE Asset	11,033
Variable Interest Entity, Funded Exposure, Debt Investment	0
Variable Interest Entity, Funded Exposure, Equity Invesment	1
Variable Ineterest Entity, Unfunded Exposure, Funding Commitments	0
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	4,191
Variable Interest Entity, Total Exposure	4,192
CDE 20
Entity Information [Line Items]
Variable Interest Entity, Initial Consolidation, Gain (Loss)	625
Variable Interest Entity, Rights Transferred	12,500
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	11,951
Variable Interest Entity, Total Involvment with SPE Asset	11,951
Variable Interest Entity, Funded Exposure, Debt Investment	0
Variable Interest Entity, Funded Exposure, Equity Invesment	1
Variable Ineterest Entity, Unfunded Exposure, Funding Commitments	0
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	4,875
Variable Interest Entity, Total Exposure	4,876
CDE 21
Entity Information [Line Items]
Variable Interest Entity, Initial Consolidation, Gain (Loss)	625
Variable Interest Entity, Rights Transferred	12,500
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets	12,003
Variable Interest Entity, Total Involvment with SPE Asset	12,003
Variable Interest Entity, Funded Exposure, Debt Investment	0
Variable Interest Entity, Funded Exposure, Equity Invesment	1
Variable Ineterest Entity, Unfunded Exposure, Funding Commitments	0
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	4,875
Variable Interest Entity, Total Exposure	$ 4,876