Employee Benefits - Activity of Assets Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Level 3) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at prior year end	$ 1,190.7	$ 900.0
Fair value of plan assets at year end	767.4	1,190.7
Fair Value, Measurements, Recurring
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at prior year end	1,190.7
Fair value of plan assets at year end	767.4	1,190.7
Fair Value, Measurements, Recurring \| Private Equities
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at prior year end	36.9
Fair value of plan assets at year end	18.6	36.9
Fair Value, Measurements, Recurring \| Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Transfers in		19.4
Purchases	1.8	1.6
Sales	(25.7)	(9.1)
Unrealized gain (loss)	5.2	(11.4)
Fair value of plan assets at prior year end	45.3	44.8
Fair value of plan assets at year end	26.6	45.3
Fair Value, Measurements, Recurring \| Level 3 \| Private Equities
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets beginning of year	36.9	36.4
Transfers in		19.4
Purchases	1.0
Sales	(24.4)	(7.7)
Unrealized gain (loss)	5.1	(11.2)
Fair value of plan assets at year end	18.6	36.9
Fair value of plan assets at prior year end	36.9
Fair value of plan assets at year end	18.6	36.9
Fair Value, Measurements, Recurring \| Level 3 \| Fixed Income
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets beginning of year	8.4	8.4
Purchases	0.8	1.6
Sales	(1.3)	(1.4)
Unrealized gain (loss)	0.1	(0.2)
Fair value of plan assets at year end	$ 8.0	$ 8.4

Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan from actual return (loss) on assets still held.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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- Definition

Amount of investment within defined benefit plan asset category.

+ References

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

Amount, measured using unobservable input, of decrease in plan asset of defined benefit plan from sale.

+ References

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- Definition

Amount, measured using unobservable input, of increase in plan asset of defined benefit plan from purchase.

+ References

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-Name Accounting Standards Codification
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-SubTopic 20
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- Definition

Defined benefit plan, plan assets level 3 reconciliation, increase for transfers in.

+ References

No definition available.

+ Details

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