Fair Value Measurements - Additional Information (Detail) (Level 3)	6 Months Ended
Jun. 30, 2013
Investment Securities Available for Sale
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value measurements, valuation technique	Discounted cash flow
Asset backed security
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value measurements, valuation technique	An option adjusted discounted cash flow model
Fair value inputs, discount rate	6.50%
Fair value inputs, constant default rate	2.00%
Fair value inputs, loss severity	90.00%
Mortgage Servicing Rights
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value measurements, valuation technique	Based upon market prices for similar instruments and an internal discounted cash flow model
Fair value inputs, discount rate	12.00%
Mortgage Servicing Rights \| Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Prepayment speeds	10.00%
Mortgage Servicing Rights \| Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Prepayment speeds	15.00%

Fair Value Inputs Default Rate

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- Definition

Prepayment Speeds

+ References

No definition available.

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- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bbb)

-URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258

+ Details

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- Definition

Loss, including interest and principal, incurred on a defaulted security, expressed as a percentage of the original principal balance, used as an input to measure fair value.

+ References

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- Definition

Description of the inputs and valuation technique(s) used to measure fair value.

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