Pension and Other Post-Retirement Benefits (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Pension Benefits
Components of net periodic (credit) expense:
Interest cost	[1]	$ 1,173	$ 1,415
Expected return on plan assets	[1]	(3,876)	(3,483)
Amortization of net actuarial loss	[1]	1,831	2,509
Net periodic (credit) expense	[1]	(872)	441
Post- Retirement Benefits
Components of net periodic (credit) expense:
Interest cost	[1]	82	128
Amortization of prior-service costs	[1]	(62)	(62)
Amortization of net actuarial loss	[1]	6	31
Net periodic (credit) expense	[1]	$ 26	$ 97

[1] Amounts are included in G&A expense on the Consolidated Statements of Income and Comprehensive Income.