Goodwill and Core Deposit Intangibles - Schedule of Future Amortization Expense (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
2022 remaining	$ 12.3
2023	15.6
2024	14.6
2025	13.7
2026	12.9
Finite-Lived Intangible Asset, Expected Amortization, After Year Four	40.5
Total	109.6	$ 41.3
Core Deposits
Finite-Lived Intangible Assets [Line Items]
2022 remaining	10.9
2023	13.7
2024	12.7
2025	11.8
2026	11.0
Finite-Lived Intangible Asset, Expected Amortization, After Year Four	27.0
Total	87.1	41.3
OCRI
Finite-Lived Intangible Assets [Line Items]
2022 remaining	1.4
2023	1.9
2024	1.9
2025	1.9
2026	1.9
Finite-Lived Intangible Asset, Expected Amortization, After Year Four	13.5
Total	$ 22.5	$ 0.0

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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

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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).

+ References

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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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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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 926
-SubTopic 20
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=120154696&loc=d3e54445-107959

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
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-Section 50
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