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Minimum Regulatory Capital Requirements - Additional Information (Detail) | Jan. 01, 2019 | Dec. 31, 2015 | Dec. 31, 2014
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Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |  |
Minimum ratio of capital to risk-weighted assets |  | 8.00% | 8.00%
Minimum leverage ratio calculated as ratio of Tier 1 capital to average quarterly assets |  | 11.91% | 11.70%
Scenario, Forecast [Member] |  |  |
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |  |
Capital conservation buffer | 2.50% |  |
CapitalRequiredForCapitalAdequacyToRiskWeightedAssets | 10.50% |  |
Minimum ratio of capital to risk-weighted assets | 8.00% |  |
Minimum leverage ratio calculated as ratio of Tier 1 capital to average quarterly assets | 4.00% |  |
Capital conservation buffer at base level | 0.625% |  |
Regulatory capital requirements phase period | 4 years |  |
Scenario, Forecast [Member] | Common Equity Tier 1 Capital [Member] |  |  |
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |  |
Minimum ratio of capital to risk-weighted assets | 4.50% |  |
Capital conservation buffer | 2.50% |  |
CapitalRequiredForCapitalAdequacyToRiskWeightedAssets | 7.00% |  |
Scenario, Forecast [Member] | Tier 1 Capital [Member] |  |  |
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |  |
Minimum ratio of capital to risk-weighted assets | 6.00% |  |
CapitalRequiredForCapitalAdequacyToRiskWeightedAssets | 8.50% |  |

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- Definition Capital required for capital adequacy to risk weighted assets including capital conservation buffer. + References No definition available. + Details
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- Definition The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958570-112826 + Details
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- Definition Tier 1 Leverage Capital divided by average assets as defined in the regulations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826 + Details
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