Loans Receivable - Schedule of Subsequently Defaulted TDRs (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013 SecurityLoan	Mar. 31, 2012 SecurityLoan
TDRs That Subsequently Defaulted In Past 12 Months [Member]
Loans Receivable [Line Items]
Number of Loans	58	47
Recorded Investment	$ 16,667	$ 25,919
TDRs That Subsequently Defaulted In Past 12 Months [Member] | Residential Mortgage Loans [Member] | Mortgage - Prime [Member]
Loans Receivable [Line Items]
Number of Loans
Recorded Investment
TDRs That Subsequently Defaulted In Past 12 Months [Member] | Commercial Loans [Member] | Real Estate [Member]
Loans Receivable [Line Items]
Number of Loans	48	40
Recorded Investment	15,147	24,053
TDRs That Subsequently Defaulted In Past 12 Months [Member] | Commercial Loans [Member] | Business [Member]
Loans Receivable [Line Items]
Number of Loans	8	6
Recorded Investment	1,469	1,866
TDRs That Subsequently Defaulted In Past 12 Months [Member] | Consumer And Other Loans [Member] | Indirect Automobile [Member]
Loans Receivable [Line Items]
Number of Loans
Recorded Investment
TDRs That Subsequently Defaulted In Past 12 Months [Member] | Consumer And Other Loans [Member] | Home Equity [Member]
Loans Receivable [Line Items]
Number of Loans	1
Recorded Investment	51
TDRs That Subsequently Defaulted In Past 12 Months [Member] | Consumer And Other Loans [Member] | Credit Card [Member]
Loans Receivable [Line Items]
Number of Loans
Recorded Investment
TDRs That Subsequently Defaulted In Past 12 Months [Member] | Consumer And Other Loans [Member] | Other [Member]
Loans Receivable [Line Items]
Number of Loans	1	1
Recorded Investment
TDRs Occurring During The Period [Member] | Non-Covered TDRs [Member]
Loans Receivable [Line Items]
Number of Loans	1	13
Pre-modification Outstanding Recorded Investment	1,545	4,063
Post-modification Outstanding Recorded Investment	1,545	3,773
TDRs Occurring During The Period [Member] | Residential Mortgage Loans [Member] | Mortgage - Prime [Member] | Non-Covered TDRs [Member]
Loans Receivable [Line Items]
Number of Loans
Pre-modification Outstanding Recorded Investment
Post-modification Outstanding Recorded Investment
TDRs Occurring During The Period [Member] | Commercial Loans [Member] | Real Estate [Member] | Non-Covered TDRs [Member]
Loans Receivable [Line Items]
Number of Loans	1	11
Pre-modification Outstanding Recorded Investment	1,545	4,036
Post-modification Outstanding Recorded Investment	1,545	3,773
TDRs Occurring During The Period [Member] | Commercial Loans [Member] | Business [Member] | Non-Covered TDRs [Member]
Loans Receivable [Line Items]
Number of Loans		1
Pre-modification Outstanding Recorded Investment		27
Post-modification Outstanding Recorded Investment
TDRs Occurring During The Period [Member] | Consumer And Other Loans [Member] | Indirect Automobile [Member] | Non-Covered TDRs [Member]
Loans Receivable [Line Items]
Number of Loans
Pre-modification Outstanding Recorded Investment
Post-modification Outstanding Recorded Investment
TDRs Occurring During The Period [Member] | Consumer And Other Loans [Member] | Home Equity [Member] | Non-Covered TDRs [Member]
Loans Receivable [Line Items]
Number of Loans
Pre-modification Outstanding Recorded Investment
Post-modification Outstanding Recorded Investment
TDRs Occurring During The Period [Member] | Consumer And Other Loans [Member] | Credit Card [Member] | Non-Covered TDRs [Member]
Loans Receivable [Line Items]
Number of Loans
Pre-modification Outstanding Recorded Investment
Post-modification Outstanding Recorded Investment
TDRs Occurring During The Period [Member] | Consumer And Other Loans [Member] | Other [Member] | Non-Covered TDRs [Member]
Loans Receivable [Line Items]
Number of Loans		1
Pre-modification Outstanding Recorded Investment
Post-modification Outstanding Recorded Investment