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Western Digital Corporation 401(k) Plan - Additional Information (Details) - USD ($) $ in Millions | 12 Months Ended
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Jun. 28, 2019 | Jun. 29, 2018 | Jun. 30, 2017
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 | $ 34 | $ 35 | $ 36
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 |  |

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