Pension and Postretirement Benefit Plans (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($)
Pension benefits
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 11.4
Estimated minimum contributions	36.5
Postretirement Health Coverage
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	0.3
Estimated minimum contributions	$ 1.5