Number Of Banking Offices Acquired

No definition available.

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- Definition

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Number of shares of equity interests issued or issuable to acquire entity.

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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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Price of a single share of a number of saleable stocks paid or offered to be paid in a business combination.

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No definition available.

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- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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- Definition

The amount of identifiable intangible assets recognized as of the acquisition date.

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- Definition

For transactions that are recognized separately from the acquisition of assets and assumptions of liabilities in the business combination, such as related to pre-existing relationships with the acquiree, this element represents the disclosure of the amount of acquisition related costs.

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- Definition

Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition.

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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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Amount of increase (decrease) 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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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Acquisitions - Narrative (Details) $ / shares in Units, $ in Millions		12 Months Ended
	Feb. 01, 2022 USD ($) office $ / shares shares	Dec. 31, 2022 USD ($) segment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Business Acquisition [Line Items]
Finite-Lived Intangible Assets, Net		$ 97.0	$ 41.3
Goodwill		$ 1,100.9	621.6	$ 621.6
Number of operating segments \| segment		1
Finite-lived intangible assets acquired		$ 72.9
Estimated useful lives of related deposits		12 years
Acquisition related expenses		$ 118.9	11.6	$ 0.0
Change in goodwill		(36.7)
Core Deposits Intangibles
Business Acquisition [Line Items]
Finite-Lived Intangible Assets, Net		75.9	41.3
Finite-lived intangible assets acquired		$ 50.1
Estimated useful lives of related deposits	10 years	10 years
Great Western Bank
Business Acquisition [Line Items]
Core deposit intangible assets	$ 50.1
Number of banking offices \| office	174
Total consideration paid	$ 1,723.3
Goodwill	479.3
Great Western Bank \| First Interstate Foundation
Business Acquisition [Line Items]
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Costs	21.5
Great Western Bank \| Scott Family
Business Acquisition [Line Items]
Business Combination, Separately Recognized Transactions, Additional Disclosures, Acquisition Costs	$ 8.2
Great Western Bank \| Class A Common Stock
Business Acquisition [Line Items]
Common stock issued (in shares) \| shares	46,879,601
Business Acquisition, Share Price \| $ / shares	$ 36.76
Great Western Bank \| Customer Relationships
Business Acquisition [Line Items]
Estimated useful lives of related deposits	12 years
Acquisition Related Costs as Defined by ASC 805
Business Acquisition [Line Items]
Acquisition related expenses		$ 26.8	$ 9.0