Retirement Plans and Other Post-Retirement Benefits - Schedule of Defined Benefit Plan Weighted-Average Assumptions Used in Computing Net Periodic Benefit Cost (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate - benefit expense	4.34%	3.85%	4.44%
Future compensation growth rate	2.50%	3.00%	3.00%
Expected long-term rate of return on plan assets	4.50%	7.25%	7.25%
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate - benefit expense	4.19%	3.68%	4.18%