Pension and Other Postretirement Employee Benefits (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Feb. 29, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Funding of pension and other postretirement benefit plans	$ 1,546,000	$ 1,714,000
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Change in monthly retirement benefit amount	0
Non-cash pretax settlement charge	43,000,000.0
Reduction in funded status of qualified pension plans	(26,200,000)
Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Deferred contribution	$ 4,400,000
Qualified Plan [Member] | Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate used to measure projected benefit obligations for qualified pension plans	2.95%			3.40%
Qualified Plan [Member] | Pension Plans [Member] | Funded with Plan Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Transfer of outstanding pension benefit obligation related to qualified pension plans to insurance company			$ 101,100,000
Reduction in funded status of qualified pension plans	$ 26,200,000