Commitments - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2012
Commitments Disclosure [Line Items]
Payment for settlement of any and all claims and disputes related to mortgage loans sold	$ 3,520
Countrywide Home Loans Settlement	3,520
Standby Letters of Credit
Commitments Disclosure [Line Items]
Financial guaranties, maximum potential amount of future payments under standby letters of credit	19,217
Financial guaranties, liabilities associated with standby letter of credit agreements	$ 192
Standby Letters of Credit \| Minimum
Commitments Disclosure [Line Items]
Financial guaranties, standby letters of credit outstanding maturities range	1 year
Standby Letters of Credit \| Maximum
Commitments Disclosure [Line Items]
Financial guaranties, standby letters of credit outstanding maturities range	3 years

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

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

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 45

-Paragraph 13

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Name:	us-gaap_GuaranteeObligationsCurrentCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant