Postretirement Benefit Plans - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 28, 2018	Dec. 29, 2017	Dec. 28, 2018	Dec. 29, 2017
Pension
Net periodic benefit income
Service cost	$ 9	$ 9	$ 18	$ 19
Interest cost	53	49	105	97
Expected return on plan assets	(96)	(92)	(191)	(184)
Amortization of net actuarial gain	0	0	0	0
Total net periodic benefit income	(34)	(34)	(68)	(68)
Other Benefits
Net periodic benefit income
Service cost	0	1	0	1
Interest cost	2	2	4	4
Expected return on plan assets	(4)	(4)	(8)	(8)
Amortization of net actuarial gain	(1)	(1)	(3)	(1)
Total net periodic benefit income	$ (3)	$ (2)	$ (7)	$ (4)