Net Periodic Pension Cost for Defined Benefit Plans (Detail) - USD ($) $ in Thousands	11 Months Ended	12 Months Ended
	Oct. 02, 2015	Sep. 29, 2017	Sep. 30, 2016
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 11,811	$ 15,108	$ 12,861
Interest cost	16,159	15,553	18,095
Expected return on plan assets	(23,872)	(25,866)	(24,491)
Settlement	3,522	21	2
Amortization of prior service cost	404	490	487
Amortization of actuarial (gain) loss	5,165	7,643	6,590
Net periodic cost (benefit)	13,189	12,949	13,544
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	359	385	342
Interest cost	464	335	473
Expected return on plan assets	0	0	0
Settlement	0	0	0
Amortization of prior service cost	(63)	(5)	(17)
Amortization of actuarial (gain) loss	0	0	0
Net periodic cost (benefit)	$ 760	$ 715	$ 798