Benefit Plans, Amounts Recognized in Accumulated Other Comprehensive Income, net of Related Tax Effects (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Amounts recognized in accumulated other comprehensive income [Abstract]
Amount recognized end of year	$ 96.1	$ 69.7
Accumulated benefit obligation	450.5	389.9
Pension Benefits [Member]
Amounts recognized in accumulated other comprehensive income [Abstract]
Net actuarial (gain) loss	99.6	73.5
Prior service cost	0.1	0.1
Amount recognized end of year	99.7	73.6
Post-Retirement Benefits [Member]
Amounts recognized in accumulated other comprehensive income [Abstract]
Net actuarial (gain) loss	(3.7)	(4.1)
Prior service cost	0.0	0.0
Amount recognized end of year	$ (3.7)	$ (4.1)

Amount, after tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669686-108580

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Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

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Amount, after tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Amount, after tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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