Pensions and Other Benefits - Summary of Pension Plan Asset Allocation and Current Weighted Average Policy Range (Details) - Pension Plan, Defined Benefit	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Asset allocation target	100.00%
Percentage of plan assets	100.00%	100.00%
Cash and cash equivalents
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Asset allocation target	1.20%
Percentage of plan assets	0.90%	1.10%
Fixed income
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Asset allocation target	24.10%
Percentage of plan assets	24.60%	25.60%
Public equity
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Asset allocation target	45.10%
Percentage of plan assets	54.50%	50.20%
Real estate and infrastructure
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Asset allocation target	9.80%
Percentage of plan assets	6.80%	7.70%
Private debt
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Asset allocation target	9.80%
Percentage of plan assets	2.40%	1.30%
Absolute return
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Asset allocation target	10.00%
Percentage of plan assets	10.80%	14.10%
Minimum | Cash and cash equivalents
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Target asset allocation percentages	0	0
Minimum | Fixed income
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Target asset allocation percentages	0.2	0.2
Minimum | Public equity
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Target asset allocation percentages	0.35	0.35
Minimum | Real estate and infrastructure
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Target asset allocation percentages	0.04	.04
Minimum | Private debt
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Target asset allocation percentages	0.04	0.04
Minimum | Absolute return
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Target asset allocation percentages	0.04	0.04
Maximum | Cash and cash equivalents
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Target asset allocation percentages	0.1	0.10
Maximum | Fixed income
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Target asset allocation percentages	0.4	0.4
Maximum | Public equity
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Target asset allocation percentages	0.55	0.55
Maximum | Real estate and infrastructure
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Target asset allocation percentages	0.13	0.13
Maximum | Private debt
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Target asset allocation percentages	0.13	0.13
Maximum | Absolute return
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Target asset allocation percentages	0.13	0.13