Pension and Other Postretirement Benefits - Assumptions Used (Details) - United States [Member]	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Assumptions for pension and other postretirement benefits [Abstract]
Mortality table for pension and postretirement benefit obligations, current year	RP 2014 with MP 2018 projection scale
Mortality table for pension and postretirement benefit obligations, prior year	RP 2014 with MP 2017 projection scale
Pension Benefits [Member]
Assumptions for pension and other postretirement benefits [Abstract]
Discount rate: Benefit obligation	4.23%	3.51%
Discount rate: Benefit cost	3.51%	3.95%
Expected long-term return on plan assets: Benefit cost	7.00%	7.25%
Other Postretirement Benefits [Member]
Assumptions for pension and other postretirement benefits [Abstract]
Discount rate: Benefit obligation	4.09%	3.37%
Discount rate: Benefit cost	3.37%	3.70%
Expected long-term return on plan assets: Benefit cost	5.00%	5.00%