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Regulatory Matters - Capital Ratios and Amounts of Company and its Banking Subsidiaries (Detail) $ in Millions | Dec. 31, 2024 USD ($) | Dec. 31, 2023 USD ($)
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M&T |  |
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |
Amount | $ 18,299 | $ 16,908
Ratio | 0.1168 | 0.1098
Amount | $ 20,692 | $ 18,918
Ratio | 0.1321 | 0.1229
Amount | $ 23,073 | $ 21,533
Ratio | 0.1473 | 0.1399
Amount | $ 20,692 | $ 18,918
Ratio | 0.1017 | 0.0943
M&T Bank |  |
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |
Amount | $ 19,233 | $ 17,667
Ratio | 0.1232 | 0.1153
Amount | $ 19,233 | $ 17,667
Ratio | 0.1232 | 0.1153
Amount | $ 21,387 | $ 19,884
Ratio | 0.1370 | 0.1297
Amount | $ 19,233 | $ 17,667
Ratio | 0.0948 | 0.0883
Wilmington Trust, N.A. |  |
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |
Amount | $ 603 | $ 583
Ratio | 2.6964 | 2.6348
Amount | $ 603 | $ 583
Ratio | 2.6964 | 2.6348
Amount | $ 604 | $ 584
Ratio | 2.6988 | 2.6385
Amount | $ 603 | $ 583
Ratio | 0.8337 | 0.8600

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- Definition Amount of total capital as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477270/942-505-50-1 + Details
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- Definition Ratio of total risk-based capital to risk-weighted assets as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477270/942-505-50-1 + Details
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- Definition Amount of Common Equity Tier 1 risk-based capital as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477270/942-505-50-1 + Details
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- Definition Amount of Tier 1 leverage capital as defined by regulatory framework. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 505 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (c)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477270/942-505-50-1 + Details
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