Schedule of Net Periodic Benefit Cost (Detail) - Pension Plan And Supplemental Plan - USD ($) $ in Thousands	4 Months Ended	5 Months Ended	12 Months Ended
	Jul. 31, 2017	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Net Period Benefit Cost Assumptions [Line Items]
Service cost	$ 393	$ 546	$ 427	$ 294
Interest cost	1,313	1,599	3,751	3,605
Expected return on plan assets	(691)	(882)	(2,375)	(2,042)
Administrational expenses	3	19	71	36
Payroll tax of net pension costs		29	55	42
Amortization of net actuarial losses		131	(592)	30
Recognized actuarial loss	748
Settlement/Curtailment (gain) loss		(99)	(219)	335
Net periodic pension cost	$ 1,766	$ 1,343	$ 1,118	$ 2,300