Western Digital Corporation 401(k) Plan - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Jul. 03, 2020	Jun. 28, 2019	Jun. 29, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer matching contribution, percent of match	50.00%
Defined contribution plan, employer matching contribution, percent of employees' gross pay	6.00%
Defined contribution plan, employer discretionary contribution amount	$ 33	$ 34	$ 35
Pre-Tax
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, maximum annual contributions per employee, percent	30.00%
Post-Tax
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, maximum annual contributions per employee, percent	10.00%
After Amendment
Defined Benefit Plan Disclosure [Line Items]
Company contributions vest period	2 years