Pension and Employee Benefit Plans - Components of Pension and Employee Benefit Expenses (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 258	$ 326	$ 516	$ 652
Expected return on plan assets	(350)	(313)	(700)	(627)
Amortization of net actuarial loss	65	65	130	132
Net periodic benefit (gain) cost	(27)	78	(54)	157
Health Care Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1	1	1	1
Amortization of loss	2	2	4	4
Net periodic benefit (gain) cost	$ 3	$ 3	$ 5	$ 5