Pension Plans and Other Postretirement Benefits - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019	Sep. 28, 2019
Components of net periodic benefit costs included in operating expenses [Abstract]
Contribution to defined pension benefit plan			$ 2,030	$ 4,335
Settlement charge			900	0
Estimated obligation due to full withdrawal multi employer pension plans	$ 20,654		20,654		$ 21,441
Defined Benefit Pension Plan [Member]
Components of net periodic benefit costs included in operating expenses [Abstract]
Defined benefit plan expected future benefit payments	3,800		3,800
Settlement threshold amount	2,880
Settlement charge	900	$ 0	900	$ 0
Defined Benefit Pension Plan [Member] | Other, Net [Member]
Components of net periodic benefit costs included in operating expenses [Abstract]
Contribution to defined pension benefit plan			2,030
Post-Retirement Benefits [Member]
Components of net periodic benefit costs included in operating expenses [Abstract]
Defined benefit plan expected future benefit payments	$ 970		970
Post-Retirement Benefits [Member] | Other, Net [Member]
Components of net periodic benefit costs included in operating expenses [Abstract]
Employer contribution for postretirement health care and life insurance			$ 644