Employee Benefits - Contributions to Employee Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Mar. 30, 2019	Jun. 30, 2018	Mar. 31, 2018	Dec. 29, 2018
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to employee benefit plans	$ 5		$ 19	$ 287
Total current year projected employer contributions	25
Pension
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to employee benefit plans	1		15	270
Total current year projected employer contributions	7
Nonpension postretirement
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to employee benefit plans	4		$ 4	$ 17
Total current year projected employer contributions	$ 18
United States | Pension
Defined Benefit Plan Disclosure [Line Items]
Employer discretionary contribution amount		$ 250