Other Assets - Affordable Housing and Other Tax Credit Investment Partnerships (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Affordable housing and other tax credit investment partnership interests
Investment partnership interest	$ 207.4		$ 206.9
Affordable housing tax credits and other benefits recognized	9.6	$ 7.4
Included in other assets \| Provision for income taxes
Affordable housing and other tax credit investment partnership interests
Amortization	7.7	$ 6.1
Included in other liabilities \| VIEs, not primary beneficiary
Affordable housing and other tax credit investment partnership interests
Unfunded commitments to fund low-income housing partnerships	$ 77.2		$ 80.7

Amount of affordable housing tax credits and other tax benefits recognized.

Reference 1: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 323
-SubTopic 740
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481543/323-740-50-2

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Amount of investment in qualified affordable housing projects.

+ References

Reference 1: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 323
-SubTopic 740
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481543/323-740-50-2

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Amount of amortization expense of investment in qualified affordable housing projects.

+ References

Reference 1: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 323
-SubTopic 740
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481543/323-740-50-2

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Amount of commitment or contingent commitments to qualified affordable housing project investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 323
-SubTopic 740
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481543/323-740-50-2

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