Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Holding Gain (Loss)

No definition available.

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- Definition

Percentage of voting equity interests acquired at the acquisition date in the business combination.

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- Definition

This element represents the amount of any measurement period adjustment (as defined) realized during the reporting period to equity interests acquired in connection with a business combination for which the initial accounting was incomplete.

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- Definition

This element represents the amount of any measurement period adjustment (as defined) realized during the reporting period to intangibles acquired in connection with a business combination for which the initial accounting was incomplete.

+ References

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- Definition

Amount of intangible assets, excluding goodwill, acquired at the acquisition date.

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- Definition

Fair value at acquisition-date of the equity interest in the acquiree held by the acquirer, immediately before the acquisition date for businesses combined in stages.

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- Definition

Percentage of voting equity interests acquired in a business combination achieved in stages, including equity interests in the acquiree held by the acquirer immediately before the acquisition date and acquired at the acquisition date.

+ References

No definition available.

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- Definition

Percentage of equity in the acquiree held by the acquirer immediately before the acquisition date in a business combination.

+ References

No definition available.

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- Definition

Amount classified as accounts, notes and loans receivable attributable to disposal group held for sale or disposed of.

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- Definition

Amount of gain (loss) from sale and disposal of integrated set of activities and assets capable of being conducted and managed for purpose of providing return in form of dividend, lower cost, or other economic benefit to investor, owner, member and participant.

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- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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- Definition

Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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- Definition

Amount of (increase) decrease to an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from the subsequent recognition of deferred tax assets.

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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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No definition available.

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Acquisition, Divestiture, and Discontinued Operations - Additional Information (Detail) - USD ($) $ in Millions				3 Months Ended		9 Months Ended
	May 04, 2018	Jun. 30, 2017	Jun. 29, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Oct. 02, 2017	Jul. 01, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill				$ 2,516		$ 2,516		$ 2,538
Gain on sale						83	$ 0
Cain Brothers & Company, LLC. [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Intangible assets acquired									$ 30
Goodwill									$ 53
HelloWallet Holdings, LLC [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Intangible assets acquired										$ 12
Goodwill										$ 17
Key Merchant Services, LLC [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Intangible assets acquired				85	$ 95	85	95
Goodwill					$ 1		$ 1
Business acquisition, percentage of coting interests acquired					51.00%		51.00%
Business combination, percentage held before acquisition date			49.00%
Business combination, ownership percentage					100.00%		100.00%
Exchange of First Niagara preferred stock for KeyCorp preferred stock			$ 74		$ 69
Business combination, noncash holding gain		$ 64			59
Business combination, estimated fair value of equity interest					5
Measurement-period adjustment, intangible assets					$ 10
Goodwill, subsequent recognition of deferred tax asset				2
Tax adjustment on previous fair value measurements						4
Disposal Group, Not Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale	$ 73			5
Discontinued Operations [Member] \| Government Guaranteed Loans [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loans included in divestiture				$ 1,100		$ 1,100		$ 1,300