Pension And Other Postretirement Benefits Benefit Obligation (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Vesting percentage	100.00%
Required term of service to be eligible for plan match	one year of service and 1,000 hours of service
Award vesting period	3 years
Employer contributions	$ 11,800,000	$ 1,700,000
Expected employer contributions remainder of year	30,000,000.0
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Assets held in postretirement benefits plan	$ 0		$ 0