Retirement and Postretirement Employee Benefit Plans - Narrative (Details) $ in Thousands		12 Months Ended
	Oct. 01, 2022	Sep. 30, 2023 USD ($) plan shares	Sep. 30, 2022 USD ($) shares	Sep. 30, 2021 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Recovery period		15 years
Employee Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Vesting period		3 years
Employer contributions		$ 8,000	$ 8,500
Accounts receivable		$ 400	2,400
Employee Pension Plan | Minimum
Defined Benefit Plan Disclosure [Line Items]
Medium-term horizon		3 years
Employee Pension Plan | Maximum
Defined Benefit Plan Disclosure [Line Items]
Medium-term horizon		5 years
Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		$ 0	0
Settlement charge		(1,030)	0	$ (9,151)
Lump sum settlement		0	0
Assets held-in-trust		31,500	30,200
Postretirement Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		$ 0	$ 1,600
Percent of projected claims paid		80.00%
Remaining percent of claims paid by participant		20.00%
Postretirement Plan | Minimum
Defined Benefit Plan Disclosure [Line Items]
Expected contribution amount		$ 10,000
Postretirement Plan | Maximum
Defined Benefit Plan Disclosure [Line Items]
Expected contribution amount		$ 15,000
Company stock | Employee Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Shares held by plan (in shares) | shares		716,700	716,700
Percent of plan assets		15.10%	15.30%
Dividend income		$ 2,100	$ 1,900
Diversified investment funds | Postretirement Plan
Defined Benefit Plan Disclosure [Line Items]
Percent of plan assets		98.20%	97.70%
Maximum investment percent		75.00%
Supplemental Executive Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Number of nonqualified supplemental plans offered | plan		3
Supplemental Executive Benefit Plan | Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Percent of covered compensation		75.00%
1998 Supplemental Executive Retirement Plan, Defined Benefit | Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Percent of covered compensation		60.00%
2009 Supplemental Executive Retirement Plan, Defined Benefit | Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Vesting period		3 years
Contribution percent		10.00%
Contribution percent for members		25.00%
Attainment age		55 years
Retirement Savings Plan
Defined Benefit Plan Disclosure [Line Items]
New employee contribution percentage		4.00%
Years of service		1 year
Maximum of eligible compensation		65.00%
Employer matching, percent of employee salary	10.00%	4.00%
Automatic increase feature	1.00%
Deferral rate	10.00%
Percent of employee contribution		100.00%
Fixed annual contribution percent		4.00%
Contribution plan cost		$ 23,900	$ 21,900	20,600
Percent of common stock outstanding		1.40%	1.60%
Executive Officer | Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Settlement charge		$ (1,000)		(9,200)
Lump sum settlement		$ 5,600		$ 25,700