Carrying Amount and Classification of Assets Related to the Corporation's Variable Interests in Non-Consolidated VIEs and Maximum Exposure to Loss (Detail) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010
Assets
Assets	$ 109,125	$ 110,019	$ 109,322
Maximum exposure to loss	109,125	110,019	109,322
Servicing Asset At Fair Value Amount
Assets
Assets	106,326	107,313	106,428
Servicing Asset At Fair Value Amount \| Mortgage servicing rights
Assets
Assets	106,326	107,313	106,428
Other assets
Assets
Assets	2,799	2,706	2,894
Other assets \| Servicing advances
Assets
Assets	$ 2,799	$ 2,706	$ 2,894

The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph b
-URI http://asc.fasb.org/extlink&oid=6970148&loc=d3e5728-111685

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS140-4/FIN46(R)
-Paragraph C6
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6970148&loc=d3e5747-111685

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant