Loans and Allowance for Loan Losses - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Receivables [Abstract]
Interest income recognized on accruing troubled debt restructuring	$ 2.5	$ 2.0	$ 0.2
Interest income recognized on nonaccrual loans	1.9	0	0
Lost interest income on nonaccrual loans	$ 0.4	$ 0.8	$ 1.4
Number of past due days for loans modified as TDR	30 days	30 days

Number of past due days for loans modified as TDR.

No definition available.

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- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5212-111524

+ Details

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- Definition

Amount of interest income recognized on a cash-basis method of accounting that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5212-111524

+ Details

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- Definition

Reflects the amount of additional interest income that would have been recorded if impaired or nonperforming loans were instead current, in compliance with their original terms, and outstanding throughout the reporting period or since origination (if held for part of the period).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 40

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18794-111554

+ Details

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- Details

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