Benefit Plans - Schedule of Assumptions (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension plans
Benefit obligation assumptions
Discount rate	2.68%	3.73%	4.00%
Rate of compensation increase	3.68%	3.77%	3.96%
Net periodic benefit expense assumptions
Discount rate	3.70%	4.00%	3.94%
Expected long-term return on plan assets	4.37%	4.17%	4.05%
Rate of compensation increase	3.72%	3.96%	3.96%
Other post-retirement plans
Benefit obligation assumptions
Discount rate	2.81%	3.95%	3.40%
Net periodic benefit expense assumptions
Discount rate	3.95%	3.40%	3.80%