Pension Plans and Other Postretirement Benefits (Tables)

6 Months Ended

Mar. 31, 2018

Defined Benefit Pension Plans And Defined Benefit Postretirement Plans Disclosure [Abstract]

Components of Net Periodic Benefit Costs

The following table provides the components of net periodic benefit costs:

	Pension Benefits
	Three Months Ended						Six Months Ended
	March 31,			March 25,			March 31,			March 25,
	2018			2017			2018			2017
Interest cost	$	944		$	1,041		$	1,888		$	2,082
Expected return on plan assets		(473	)		(537	)		(947	)		(1,075	)
Amortization of net loss		921			1,300			1,842			2,600
Net periodic benefit cost	$	1,392		$	1,804		$	2,783		$	3,607

	Postretirement Benefits
	Three Months Ended						Six Months Ended
	March 31,			March 25,			March 31,			March 25,
	2018			2017			2018			2017
Interest cost	$	69		$	96		$	138		$	193
Amortization of prior service credits		(124	)		—			(248	)		—
Amortization of net (gain)		(164	)		(97	)		(328	)		(194	)
Net periodic benefit cost	$	(219	)	$	(1	)	$	(438	)	$	(1	)