Loans and Leases - Average Recorded Investment in Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2014	Mar. 31, 2013
Financing Receivable, Modifications [Line Items]
Average investment in impaired loans	$ 1,160	$ 3,334
Commercial and Other Loans [Member]
Financing Receivable, Modifications [Line Items]
Average investment in impaired loans	25	30
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Average investment in impaired loans	911	3,081
Consumer Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Average investment in impaired loans	$ 224	$ 223

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5258-111524

Name:	us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration