Pension Plans, Postretirement and Other Employee Benefits - Healthcare Trend (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Initial health care cost trend rate	6.30%	6.60%	6.90%
Ultimate health care cost trend rate	4.90%	4.90%	4.90%