Loans Modified Troubled Debt Restructuring By Class (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Financing Receivable, Impaired [Line Items]
Number of Modifications	14	[1]	113	[1]
Unpaid Principal Balance (at period end)	$ 2,580	[1],[2]	$ 95,778	[1],[2]
Balance in ALLL, Prior to Modification	1,728	[1],[3]	13,777	[1],[3]
Balance in ALLL, At Period End	395	[1],[3]	30,183	[1],[3]
Residential
Financing Receivable, Impaired [Line Items]
Number of Modifications	0	[1]	40	[1]
Unpaid Principal Balance (at period end)			5,964	[1],[2]
Balance in ALLL, Prior to Modification			318	[1],[3]
Balance in ALLL, At Period End			477	[1],[3]
Commercial and industrial
Financing Receivable, Impaired [Line Items]
Number of Modifications	3	[1]	14	[1]
Unpaid Principal Balance (at period end)	169	[1],[2]	6,439	[1],[2]
Balance in ALLL, Prior to Modification	206	[1],[3]	2,841	[1],[3]
Balance in ALLL, At Period End	139	[1],[3]	3,007	[1],[3]
Land and construction
Financing Receivable, Impaired [Line Items]
Number of Modifications	2	[1]	16	[1]
Unpaid Principal Balance (at period end)	546	[1],[2]	50,820	[1],[2]
Balance in ALLL, Prior to Modification	548	[1],[3]	4,553	[1],[3]
Balance in ALLL, At Period End	36	[1],[3]	16,259	[1],[3]
Multi-family
Financing Receivable, Impaired [Line Items]
Number of Modifications	0	[1]	10	[1]
Unpaid Principal Balance (at period end)			9,891	[1],[2]
Balance in ALLL, Prior to Modification			2,725	[1],[3]
Balance in ALLL, At Period End			4,477	[1],[3]
Retail/office
Financing Receivable, Impaired [Line Items]
Number of Modifications	3	[1]	14	[1]
Unpaid Principal Balance (at period end)	899	[1],[2]	9,433	[1],[2]
Balance in ALLL, Prior to Modification	383	[1],[3]	1,006	[1],[3]
Balance in ALLL, At Period End	176	[1],[3]	1,541	[1],[3]
Other commercial real estate
Financing Receivable, Impaired [Line Items]
Number of Modifications	4	[1]	13	[1]
Unpaid Principal Balance (at period end)	934	[1],[2]	12,927	[1],[2]
Balance in ALLL, Prior to Modification	591	[1],[3]	2,334	[1],[3]
Balance in ALLL, At Period End	44	[1],[3]	4,422	[1],[3]
Education
Financing Receivable, Impaired [Line Items]
Number of Modifications	0	[1]	0	[1]
Other consumer
Financing Receivable, Impaired [Line Items]
Number of Modifications	2	[1]	6	[1]
Unpaid Principal Balance (at period end)	$ 32	[1],[2]	$ 304	[1],[2]

[1] Loans modified in a TDR that were fully paid down, charged-off or foreclosed upon by period end are not reported in this table.

[2] The unpaid principal balance is inclusive of all partial paydowns and charge-offs since the modification date.

[3] The balance in the ALLL represents any specific component of the allowance for loan losses associated with these loans.