Commitments and Contingent Liabilities - Additional Information (Detail) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Contingencies And Commitments [Line Items]
Mortgage loans in the process of origination	$ 7,845,000	$ 9,008,000
Mortgage loans held for sale	$ 5,106,000	$ 1,441,000
Minimum
Contingencies And Commitments [Line Items]
Mortgage loans in the process of origination, funding period	60 days
Maximum
Contingencies And Commitments [Line Items]
Mortgage loans in the process of origination, funding period	90 days

Carrying amount of mortgage loans to individuals not classified as held for investment but are held-for-sale.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 310

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6490309&loc=d3e48678-111004

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Permanent Investor

-URI http://asc.fasb.org/extlink&oid=6520390

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6375948&loc=d3e4428-111522

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 65

-Paragraph 1, 34

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher OTS

-Name Federal Regulation (FR)

-Number Title 12

-Section 563c.102

-Paragraph 8

-Subparagraph h

-Chapter V

-Subsection I

-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(a)(3))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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