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Minimum Regulatory Capital Requirements - Additional Information (Detail) | Dec. 31, 2020 | Dec. 31, 2019 | Jan. 01, 2019
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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 | 8.0
Minimum ratio of capital to risk-weighted assets including capital conservation buffer |  |  | 10.50%
Minimum leverage ratio calculated as ratio of Tier 1 capital to average quarterly assets | 9.08 | 10.02 | 4.0
Common Equity Tier 1 Capital [Member] |  |  |
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items] |  |  |
Minimum ratio of capital to risk-weighted assets |  |  | 4.5
Capital conservation buffer |  |  | 2.50%
Minimum ratio of capital to risk-weighted assets including capital conservation buffer |  |  | 7.00%
Tier 1 Capital [Member] |  |  |
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items] |  |  |
Minimum ratio of capital to risk-weighted assets |  |  | 6.0
Minimum ratio of capital to risk-weighted assets including capital conservation buffer |  |  | 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 Risk weighted assets capital conservation buffer. + References No definition available. + Details
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- Definition Ratio of minimum total risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958570-112826 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
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- Definition Ratio of Tier 1 capital to average assets as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826 + Details
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