Benefit Plans - Fair Value of Plan Assets (Details) - Pension Plan - USD ($) $ in Thousands	Sep. 29, 2018	Sep. 30, 2017	Oct. 01, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 123,471	$ 112,311	$ 100,662
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	123,471	112,311
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	86,410	80,795
Equity securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Equity securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	86,410	80,795
Equity securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	37,061	31,516
Debt securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Debt securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	37,061	31,516
Debt securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0