Post-Retirement Benefits - Schedule of Net Periodic Benefit Cost and Other Amounts Recognized in Other Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Employee Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 180	$ 250	$ 540	$ 750
Expected return on plan assets	(479)	(513)	(1,436)	(1,539)
Amortization of prior net loss	132	145	396	435
Settlement charges			272
Net periodic cost (benefit)	(167)	(118)	(228)	(354)
Supplemental Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	90	78	248	373
Interest cost	28	36	89	88
Amortization of prior net loss	11	9	34	27
Net periodic cost (benefit)	$ 129	$ 123	$ 371	$ 488