Benefit Plans (Effects of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates) (Details)	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Defined benefit plan, effect of one percentage point increase on service and interest cost components, percent	7.50%
Defined benefit plan effect of one percentage point increase on accumulated postretirement benefit obligation percentage	5.60%
Defined benefit plan effect of one percentage point decrease on service and interest cost components percentage	(6.30%)
Defined benefit plan effect of one percentage point decrease on accumulated postretirement benefit obligation percentage	(4.80%)