Pension Plans and Other Postretirement Benefits - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 24, 2017	Jun. 25, 2016	Sep. 24, 2016
Components of net periodic benefit costs included in operating expenses [Abstract]
Contribution to defined pension benefit plan	$ 7,542	$ 0
Estimated obligation due to withdrawal multi employer pension plans	22,960		$ 24,205
Defined Benefit Pension Plan [Member]
Components of net periodic benefit costs included in operating expenses [Abstract]
Defined benefit plan expected contribution to be paid for fiscal year	9,527
Contribution to defined pension benefit plan	7,542
Post-Retirement Benefits [Member]
Components of net periodic benefit costs included in operating expenses [Abstract]
Defined benefit plan expected contribution to be paid for fiscal year	922
Employer contribution for postretirement health care and life insurance	$ 899