Employee and Retiree Benefit Plans - Weighted Average Asset Allocation for Funded Pension Benefit Plans (Details)	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	100.00%	100.00%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	58.10%	54.90%
Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	24.00%	26.20%
Alternatives
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	13.20%	17.30%
Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	4.70%	1.60%
Domestic Plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	56.00%
Domestic Plan | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	28.00%
Domestic Plan | Alternatives
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	11.40%
Domestic Plan | Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	4.60%
Domestic Plan | Minimum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target allocations of plan assets	40.00%
Domestic Plan | Minimum | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Target allocations of plan assets	28.00%
Domestic Plan | Minimum | Alternatives
Defined Benefit Plan Disclosure [Line Items]
Target allocations of plan assets	0.00%
Domestic Plan | Minimum | Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Target allocations of plan assets	0.00%
Domestic Plan | Maximum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target allocations of plan assets	70.00%
Domestic Plan | Maximum | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Target allocations of plan assets	60.00%
Domestic Plan | Maximum | Alternatives
Defined Benefit Plan Disclosure [Line Items]
Target allocations of plan assets	18.00%
Domestic Plan | Maximum | Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Target allocations of plan assets	15.00%
Canadian Plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	31.00%
Canadian Plan | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	68.00%
Canadian Plan | Alternatives
Defined Benefit Plan Disclosure [Line Items]
Target allocations of plan assets	0.00%
Weighted average asset allocation	0.00%
Canadian Plan | Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	1.00%
Canadian Plan | Maximum | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target allocations of plan assets	0.00%
Canadian Plan | Maximum | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Target allocations of plan assets	98.00%
Canadian Plan | Maximum | Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Target allocations of plan assets	2.00%
U.K. Plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	65.00%
U.K. Plan | Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	11.70%
U.K. Plan | Alternatives
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	18.00%
U.K. Plan | Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation	5.30%