Benefit Plans - Fair Value of Plan Assets (Details) - Pension Plan - USD ($) $ in Thousands	Sep. 28, 2019	Sep. 29, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 118,048	$ 123,471	$ 112,311
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	118,048	123,471
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	79,627	86,410
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	79,627	86,410
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	38,421	37,061
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	38,421	37,061
Debt securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0