Acquisitions - Summary of Pro Forma Financial Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2022
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Earnings Per Share, Basic	$ 0.85	$ 2.60
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$ 0.85	$ 2.60
Great Western Bank
Business Acquisition [Line Items]
Total revenues	$ 314.0	$ 883.5
Net income	$ 90.3	$ 267.8

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
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The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-Section 50
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-Topic 805
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479328/805-10-50-2

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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