Mortgage Servicing Rights - Narrative (Details) - Mortgage loans - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value [Abstract]
Mortgage servicing rights, fair value	$ 28.2	$ 24.0
Servicing asset at fair value, assumptions used to estimate fair value, weighted average life	5 years 10 months 24 days	3 years 10 months 24 days
Impairment reversals	$ 6.9	$ 9.9	$ 0.4
Permanent impairment charged against carrying value	$ 0.0
Minimum
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value [Abstract]
Servicing assets at fair value, assumptions used to estimate fair value, discount rate	8.60%	8.30%
Servicing assets at fair value, assumptions used to estimate fair value, prepayment speed	0.70%	1.20%
Maximum [Member]
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value [Abstract]
Servicing assets at fair value, assumptions used to estimate fair value, discount rate	10.40%	10.00%
Servicing assets at fair value, assumptions used to estimate fair value, prepayment speed	2.00%	2.50%

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
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Discount rate used to estimate the fair value of servicing assets and servicing liabilities.

+ References

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-Publisher FASB
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Estimated rate of prepayments of principal on servicing assets and servicing liabilities.

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Weighted average life of financial assets and financial liabilities, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition

Amount of decrease in the valuation allowance for impairment of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer from write-downs charged against the allowance.

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