Loans Held for Sale, Loan Servicing and Mortgage Origination (Detail) - Activity in the MSRs (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Dec. 31, 2011	Dec. 31, 2012	Sep. 30, 2011
Carrying value at beginning of period	$ 10,572	$ 10,663	$ 10,200
Additions
Servicing assets that resulted from transfers of financial assets	1,342	7,972	3,982
Decrease in fair value
Reclass of nonaccretable difference due to improvement in expected cash flows	(14,592)	(6,000)	0
Carrying value at end of period	10,663	13,910	10,572
Change During Period, Fair Value Disclosure [Member]
Decrease in fair value
Reclass of nonaccretable difference due to improvement in expected cash flows	(750)	(2,386)	(1,974)
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Decrease in fair value
Reclass of nonaccretable difference due to improvement in expected cash flows	$ (501)	$ (2,339)	$ (1,636)

Change in the estimate of cash flows expected to be collected, after acquisition of a loan, which results in a decrease in accretable yield (for example, as a result of an other-than-temporary impairment). This relates to loans accounted for as debt securities, with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

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The net cash outflow or inflow associated with acquisition or sale of mortgage servicing rights which is the net carrying value of capitalized servicing rights, which contractually entitle the servicer to receive fees and ancillary revenues for performing billing, collection, disbursement and recordkeeping services in connection with a mortgage portfolio. Rights may be obtained via (1) acquisition or assumption of a servicing obligation that does not relate to financial assets of the servicer or its consolidated affiliates; or (2) by originating mortgage loans and then (a) transferring the loans to a Variable Interest Entity (VIE) in a transaction that meets the necessary transfer and classification requirements, or (b) transferring the loans in a transaction that meets the requirements for sale accounting.

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- Definition

Amortized carrying amount (balance) as of the balance sheet date of an asset representing net future revenues from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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

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

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-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

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-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.

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