Investment Securities - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
May 31, 2012	Dec. 31, 2013 Security	Dec. 31, 2012 Security
Investments Debt And Equity Securities [Abstract]
Reclassification of held-to-maturity investment portfolio to available for sale	$ 269.0
Increased total shareholders' equity by reclassification	5.5
Available-for-sale securities maturity period		2 years
Prohibited from classifying security purchases as held to maturity date		May 31, 2014
Number of available-for-sale investment securities in the less than twelve month category		36	2
Number of available-for-sale investment securities in the twelve month or more category		8	8
Pledged investment securities fair value		$ 451.1	$ 103.5

Increase in stockholders equity related to reclassification of held to maturity securities.

No definition available.

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- Definition

Prohibition Date For Classifying Securities As Held To Maturity

+ References

No definition available.

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- Definition

Prohibition period for classifying securities as held to maturity.

+ References

No definition available.

+ Details

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- Definition

Number of investment positions in available-for-sale investments that have been in a continuous unrealized loss position for greater than or equal to a year for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

+ References

No definition available.

+ Details

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- Definition

Number of investment positions in available-for-sale investments in a continuous unrealized loss position for less than one year or normal operating cycle, if longer, for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

+ References

No definition available.

+ Details

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- Definition

For any transfer of securities categorized as held-to-maturity, this item represents the net carrying amount of the transferred security to another category of investments in debt and equity securities (trading or available-for-sale).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27405-111563

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- Definition

Sum of the carrying amounts as of the date of the latest financial statement presented of securities which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 50

-Paragraph 1A

-Subparagraph (b)(1)(i)

-URI http://asc.fasb.org/extlink&oid=7523297&loc=SL6224234-111729

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