Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended
Jan. 31, 2018	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock and RSUs, Granted		753,901
Fair value of RSUs/restricted stock granted to employees		$ 427
RSUs/Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock and RSUs, Granted	527,337
Award vesting period, years	3 years
Awards to employees cliff vesting	209,201
RSUs to employees that cliff vest, percentage	100.00%
RSUs to employees that cliff vest, date	Jan. 31, 2021
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of outstanding RSUs		$ 1,200
Stock price		$ 541.72
Unrecognized stock-based compensation expense		$ 575
Remaining weighted-average period		1 year 6 months
Performance-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock and RSUs, Granted	199,068	199,068
Award vesting period, years	3 years
Awards to employees cliff vesting	199,068
RSUs to employees that cliff vest, percentage	100.00%
RSUs to employees that cliff vest, date	Jan. 31, 2021
Intrinsic value of outstanding RSUs		$ 464
Stock price		$ 541.72
Unrecognized stock-based compensation expense		$ 203
Remaining weighted-average period		1 year 8 months 12 days
Restricted Stock and RSUs, Additional Grants	23,376	23,376
Fair value of RSUs/restricted stock granted to employees		$ 121
Long-Term Incentive Plans Funded by PNC [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of shares surrendered		3,900,000
Number of additional shares surrendered		103,064
Remaining shares committed by PNC for long-term incentive awards		100,000
Long-Term Incentive Plans Funded by PNC [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares committed to fund long-term incentive plans		4,000,000
Performance-Based Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation expense		$ 191
Remaining weighted-average period		5 years 8 months 12 days

Aggregate number of shares surrendered.

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Fair value of restricted stock units and restricted stock granted to employees.

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Remaining share of committed long-term incentive awards.

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- Definition

The number of additional grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

No definition available.

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- Definition

Share based compensation arrangement by share based payment award equity instruments other than options granted in period fair value.

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- Definition

Share based compensation arrangement by share based payment award equity instruments other than options surrendered in period.

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- Definition

Share based compensation arrangement by share based payment award equity instruments other than options that cliff vest.

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- Definition

Shares committed to fund long term incentive plans.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Date the equity-based award expires, in CCYY-MM-DD format.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- 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.

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Price of a single share of a number of saleable stocks of a company.

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- Definition

Percentage of vesting of share-based compensation awards.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Intrinsic value of equity-based compensation awards outstanding. Excludes stock and unit options.

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