Long-term Employee Benefits - Schedule of Assumptions Used (Details) - Pension Plan	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Discount rate to determine benefit obligation	1.12%	1.58%	2.27%
Discount rate to determine net cost	1.58%	2.27%	2.13%
Rate of future compensation increases to determine benefit obligation	2.71%	2.73%	2.68%
Rate of future compensation increases to determine net cost	2.73%	2.68%	2.69%
Rate of return on plan assets to determine net cost	3.71%	4.21%	4.47%
Cash balance interest credit rate to determine benefit obligation	0.40%	0.49%	1.13%
Cash balance interest credit rate to determine net cost	0.49%	1.13%	0.96%