Employee and Retiree Benefit Plans (Narrative) (Details) $ in Millions	9 Months Ended
Sep. 30, 2020 USD ($)
Retirement Benefits [Abstract]
Increase in pension liabilities	$ 63.0
Contributions to benefit plans	27.4
Expected benefit plan contributions to be made during the year	$ 10.3

Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Name:	us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration