Employee Benefit Plans (Weighted-Average Assumptions Used to Determine Benefit Obligations) (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Benefit obligations, Discount rate	2.43%	3.20%	4.36%
Net periodic benefit cost, Discount rate	3.20%	4.36%	3.68%
Net periodic benefit cost, Expected return on plan assets	7.25%	7.25%	7.25%