Post-Employment Benefits - Weighted-Average Assumptions Used in Determining Net Periodic Benefit Cost (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined benefit plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate for determining service cost	4.00%	3.40%	3.90%
Discount rate for determining interest cost	4.00%	3.10%	3.70%
Expected long-term rate of return on plan assets	7.60%	7.70%	7.80%
Expected rate of change in compensation	4.60%	4.40%	4.40%
Other post-employment plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate for determining service cost	4.70%	4.00%	4.90%
Discount rate for determining interest cost	4.30%	3.70%	4.10%