Securities (Investment Security Gains and Losses) (Details) - USD ($) $ in Millions		12 Months Ended
Jan. 01, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Gross Realized Debt Securities Gains		$ 1.4	$ 3.4	$ 2.4
Gross Realized Debt Securities Losses		(1.7)	(3.8)	(3.5)
Changes in Other-Than-Temporary Impairment Losses	$ (4.4)	0.0	0.0	(0.3)
Net Investment Security Losses		$ (0.3)	$ (0.4)	$ (1.4)

Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27357-111563

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Amount of realized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of other-than-temporary impairment (OTTI) on investment in debt security, recognized in earnings.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 8A
-URI http://asc.fasb.org/extlink&oid=124260329&loc=SL6284422-111562

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Amount of realized gain (loss) on investment.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.3(a))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

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