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Regulatory Matters - Additional Information (Detail) (USD $) | 1 Months Ended | 3 Months Ended | 9 Months Ended |  | 1 Months Ended | 9 Months Ended
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Jul. 31, 2013 | Apr. 30, 2013 | Jan. 31, 2013 | Oct. 31, 2012 | May 19, 2010 | Sep. 30, 2013 | Jun. 30, 2013 | Mar. 31, 2013 | Dec. 31, 2012 | Sep. 30, 2012 | Sep. 30, 2013 | Sep. 30, 2012 | Dec. 31, 2009 | Oct. 31, 2013 Subsequent Event [Member] | Sep. 30, 2013 Installment One FY Two Thousand Thirteen [Member] | Sep. 30, 2013 Installment Two FY Two Thousand Thirteen [Member] | Sep. 30, 2013 Installment Three FY Two Thousand Thirteen [Member] | Sep. 30, 2013 Installment Four FY Two Thousand Thirteen [Member] | Sep. 30, 2013 Installment Five Fy Two Thousand Thirteen [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Trust preferred securities |  |  |  |  |  | $ 32,000,000 |  |  | $ 32,000,000 |  | $ 32,000,000 |  |  |  |  |  |  |  |
Aggregate amount of restricted core elements allowed in Tier 1 capital |  |  |  |  |  |  |  |  |  |  | 25.00% |  |  |  |  |  |  |  |
Trusted preferred securities issued date |  |  |  |  | before May 19, 2010 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum level of consolidated aggregate assets allowing for inclusion of trust preferred securities in Tier Capital under Dodd-Frank Act |  |  |  |  |  |  |  |  |  |  |  |  | $ 15,000,000,000 |  |  |  |  |  |
Cash dividend on common stock |  |  |  |  |  | $ 0.12 | $ 0.11 | $ 0.10 | $ 0.09 | $ 0.00 | $ 0.33 | $ 0.00 |  |  |  |  |  |  |
Cash dividend declared on common stock | $ 0.12 | $ 0.11 | $ 0.10 | $ 0.09 |  |  |  |  |  |  |  |  |  | $ 0.12 |  |  |  |  |
Dividend declared date |  |  |  |  |  |  |  |  |  |  |  |  |  |  | Oct. 11, 2012 | Jan. 10, 2013 | Apr. 11, 2013 | Jul. 11, 2013 | Oct. 10, 2013
Dividend payable date |  |  |  |  |  |  |  |  |  |  |  |  |  |  | Dec. 10, 2012 | Mar. 08, 2013 | Jun. 10, 2013 | Sep. 10, 2013 | Dec. 10, 2013
Dividend payable date of record |  |  |  |  |  |  |  |  |  |  |  |  |  |  | Nov. 09, 2012 | Feb. 08, 2013 | May 10, 2013 | Aug. 09, 2013 | Nov. 08, 2013
Dividend suspended date |  |  |  |  |  |  |  |  |  |  | Apr. 01, 2010 |  |  |  |  |  |  |  |

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- Definition Maximum level of consolidated aggregate assets allowing for inclusion of trust preferred securities in Tier 1 capital under Dodd-Frank Act. + References No definition available. + Details
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- Definition Aggregate dividends paid during the period for each share of common stock outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
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