Commitments and contingent liabilities - Significant Industry Concentrations Related to Credit Exposure (Details) $ in Billions	Jun. 30, 2020 USD ($)
Financial institutions
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	$ 10.8
Unfunded commitments	35.5
Total exposure	46.3
Financial institutions \| Securities industry
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	1.6
Unfunded commitments	24.5
Total exposure	26.1
Financial institutions \| Banks
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	7.0
Unfunded commitments	1.1
Total exposure	8.1
Financial institutions \| Asset managers
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	1.3
Unfunded commitments	6.3
Total exposure	7.6
Financial institutions \| Insurance
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	0.1
Unfunded commitments	2.7
Total exposure	2.8
Financial institutions \| Government
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	0.1
Unfunded commitments	0.2
Total exposure	0.3
Financial institutions \| Other
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	0.7
Unfunded commitments	0.7
Total exposure	1.4
Commercial
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	2.4
Unfunded commitments	11.8
Total exposure	14.2
Commercial \| Manufacturing
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	1.1
Unfunded commitments	3.5
Total exposure	4.6
Commercial \| Services and other
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	1.1
Unfunded commitments	3.3
Total exposure	4.4
Commercial \| Energy and utilities
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	0.1
Unfunded commitments	4.1
Total exposure	4.2
Commercial \| Media and telecom
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Loans	0.1
Unfunded commitments	0.9
Total exposure	$ 1.0

The sum of loans outstanding and unfunded credit commitments

No definition available.

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Namespace Prefix:	bk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Credit commitments to extend credit to a counterparty under certain terms and conditions.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121593590&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5074-111524

+ Details

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- Details

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- Details

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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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