Goodwill and Core Deposit Intangibles - Schedule of Future Amortization Expense (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
2023 remaining	$ 3.8
2024	14.6
2025	13.7
2026	12.8
2027	10.1
Finite-Lived Intangible Asset, Expected Amortization, After Year Four	30.2
Total	85.2	$ 97.0
Core Deposits
Finite-Lived Intangible Assets [Line Items]
2023 remaining	3.4
2024	12.7
2025	11.8
2026	10.9
2027	8.2
Finite-Lived Intangible Asset, Expected Amortization, After Year Four	18.6
Total	65.6	75.9
OCRI
Finite-Lived Intangible Assets [Line Items]
2023 remaining	0.4
2024	1.9
2025	1.9
2026	1.9
2027	1.9
Finite-Lived Intangible Asset, Expected Amortization, After Year Four	11.6
Total	$ 19.6	$ 21.1

Finite-Lived Intangible Asset, Expected Amortization, After Year Four

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- Definition

Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482665/350-30-50-2

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in remainder of current fiscal year.

+ References

No definition available.

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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Amount of amortization for assets, excluding financial assets and goodwill, lacking physical substance with finite life expected to be recognized in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 926
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483154/926-20-50-5

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-Topic 350
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482665/350-30-50-2

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