Transfers and Servicing of Financial Assets (Including Mortgage Banking Activity) - Components of Mortgage Income (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Participating Mortgage Loans [Line Items]
Derivative settlements	$ (1)	$ 209	$ (1)
Gains on sales	59,156us-gaap_GainLossOnSaleOfMortgageLoans	65,393us-gaap_GainLossOnSaleOfMortgageLoans	70,811us-gaap_GainLossOnSaleOfMortgageLoans
Total mortgage income	51,797	64,197	78,053
Mortgage Income [Member]
Participating Mortgage Loans [Line Items]
Mortgage loans held for sale and derivatives	631	(4,822)	6,772
Derivative settlements	(8,743)	3,100
Gains on sales	59,156	65,393	70,811
Servicing and other income, net	753	526	470
Total mortgage income	$ 51,797	$ 64,197	$ 78,053

Income from the servicing of mortgage loans held for sale.

No definition available.

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- Definition

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5618551-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (a),(c),(d),(e)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624171-113959

+ Details

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- Definition

The noninterest income derived from mortgage banking activities (fees and commissions), excluding fees earned from servicing third-party assets.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 13

-Article 9

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.13 (d))

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

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- Definition

The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans made to finance real estate acquisitions. This element refers to the gain (loss) and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

+ References

+ Details

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- Definition

The increase (decrease) during the reporting period in the value of mortgage loans that are held with the intention to sell or be securitized in the near future.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

+ Details

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- Details

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