Pensions and Other Post-retirement Benefits - Schedule of Assumptions Used to Determine Benefit Obligations and Net Periodic Benefit Cost (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Assumptions used to determine benefit obligations, average discount rate	2.86%	3.79%
Assumptions used to determine benefit obligations, rate of compensation increase	2.93%	3.00%
Assumptions used to determine net periodic benefit cost, average discount rate, service cost	3.10%	3.34%
Assumptions used to determine net periodic benefit cost, average discount rate, interest cost	2.52%	3.34%
Assumptions used to determine net periodic benefit cost, expected return on plan assets	7.09%	7.99%
Assumptions used to determine net periodic benefit cost, rate of compensation increases	2.93%	3.00%
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Assumptions used to determine benefit obligations, average discount rate	3.05%	4.21%
Assumptions used to determine net periodic benefit cost, average discount rate, service cost	3.15%	3.57%
Assumptions used to determine net periodic benefit cost, average discount rate, interest cost	2.61%	3.57%