Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
	Jan. 01, 2022	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution, percent of employees' deferred amount				50.00%
Employer matching contribution, percent of employees' eligible annual compensation				3.50%
Forecast
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution, percent of employees' eligible annual compensation	7.00%
Employer matching contribution, percent of match (up to)	3.00%
Qualified Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 10,289	$ 8,576	$ 30,869	$ 25,725	$ 39,443	$ 32,191
Interest cost		10,108	11,388	30,324	34,165	41,714	46,416
Expected return on plan assets		(18,088)	(16,324)	(54,264)	(48,972)	(70,588)	(64,033)
Amortization of net actuarial loss		10,489	9,006	31,467	27,019	40,473	32,608
Net periodic benefit cost		12,798	12,646	38,396	37,937	51,042	47,182
SERP
Defined Benefit Plan Disclosure [Line Items]
Service cost		131	97	394	292	491	359
Interest cost		358	401	1,074	1,204	1,474	1,644
Amortization of net actuarial loss		661	451	1,981	1,353	2,433	1,608
Net periodic benefit cost		1,150	949	3,449	2,849	4,398	3,611
PBOP
Defined Benefit Plan Disclosure [Line Items]
Service cost		423	395	1,269	1,186	1,664	1,505
Interest cost		549	646	1,645	1,936	2,291	2,697
Expected return on plan assets		(810)	(852)	(2,430)	(2,556)	(3,282)	(3,345)
Amortization of prior service costs		239	289	719	867	1,007	1,185
Net periodic benefit cost		$ 401	$ 478	$ 1,203	$ 1,433	$ 1,680	$ 2,042