Additional Information Regarding Methods used to Evaluate Loan Portfolio for Impairment (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans, net	$ 31,241,635	$ 30,152,154
Additional Information Loan Portfolio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, Individually evaluated for impairment	320,341	330,422
Loans Receivable, Collectively evaluated for impairment	26,492,720	25,198,375
Loans Receivable, Acquired loans with deteriorated credit quality	3,400,624	3,753,031
Total loans, net	30,213,685	29,281,828
Additional Information Loan Portfolio \| Mortgage Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, Individually evaluated for impairment	302,571	324,427
Loans Receivable, Collectively evaluated for impairment	25,873,662	24,534,477
Loans Receivable, Acquired loans with deteriorated credit quality	3,069,827	3,366,456
Total loans, net	29,246,060	28,225,360
Additional Information Loan Portfolio \| Other loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Receivable, Individually evaluated for impairment	17,770	5,995
Loans Receivable, Collectively evaluated for impairment	619,058	663,898
Loans Receivable, Acquired loans with deteriorated credit quality	330,797	386,575
Total loans, net	$ 967,625	$ 1,056,468

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The balance of financing receivables that were acquired with deteriorated credit quality.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (h)

-URI http://asc.fasb.org/extlink&oid=7512638&loc=SL6953423-111524

+ Details

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- Definition

The balance of financing receivables that were collectively evaluated for impairment.

+ References

+ Details

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- Definition

The balance of financing receivables that were individually evaluated for impairment.

+ References

+ Details

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- Definition

Net amount of the investment in a contractual right to receive money on demand or on fixed or determinable dates that is recognized as an asset in the creditor's statement of financial position. Examples include, but are not limited to, credit card receivables, notes receivable and receivables relating to lessor's rights to payments from leases other than operating leases that have been recorded as assets. Excludes trade accounts receivable with contractual maturity of one year or less and arose from the sale of goods or services.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.3)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 3

-Article 5

+ Details

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