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Stock-Based Compensation - Narrative (Details) - USD ($) $ in Thousands | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 26, 2020 | Dec. 28, 2019 | Dec. 29, 2018 | Apr. 23, 2020 | May 01, 2019 | Apr. 26, 2019
Defined Benefit Plan Disclosure |  |  |  |  |  |
Authorized (in shares) | 900,000 |  |  |  |  |
IXYS converted awards (in shares) | 499,027 |  |  |  |  |
Allocated share based compensation | $ 19,100 | $ 19,900 | $ 28,200 |  |  |
Stock compensation expense | 18,129 | 19,046 | 27,431 |  |  |
Options intrinsic value | 20,600 | 12,500 | 38,300 |  |  |
Fair value of shares other than options vested | 9,500 | 15,500 | 20,800 |  |  |
Share-based liabilities paid | 500 | 900 | 1,100 |  |  |
Unrecognized compensation cost | $ 22,600 |  |  |  |  |
Unrecognized compensation cost, period for recognition (years) | 2 years |  |  |  |  |
Income tax benefit | $ 3,100 | $ 3,300 | $ 6,000 |  |  |
Purchase of common stock (in shares) | 175,110 | 579,916 | 391,972 |  |  |
Repurchases of common stock | $ 22,927 | $ 95,036 | $ 67,908 |  |  |
2018 Share Repurchase Program |  |  |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |  |  |
Share repurchase program authorized (in shares) |  |  |  |  | 1,000,000 |
2019 Share Repurchase Program |  |  |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |  |  |
Share repurchase program authorized (in shares) |  |  |  |  |  | 1,000,000
2020 Share Repurchase Program |  |  |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |  |  |
Share repurchase program authorized (in shares) | 1,000,000 |  |  | 1,000,000 |  |
Options |  |  |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |  |  |
Award vesting period | 4 years |  |  |  |  |
IXYS Corporation |  |  |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |  |  |
Stock compensation expense |  |  | 4,500 |  |  |
IXYS Corporation | Options |  |  |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |  |  |
Allocated share based compensation |  |  | $ 11,900 |  |  |
Minimum | Options |  |  |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |  |  |
Award vesting period | 3 years |  |  |  |  |
Award expiration period | 7 years |  |  |  |  |
Minimum | Non-vested restricted share and share unit awards |  |  |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |  |  |
Award vesting period | 3 years |  |  |  |  |
Maximum | Options |  |  |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |  |  |
Award vesting period | 5 years |  |  |  |  |
Award expiration period | 10 years |  |  |  |  |
Maximum | Non-vested restricted share and share unit awards |  |  |  |  |  |
Defined Benefit Plan Disclosure |  |  |  |  |  |
Award vesting period | 4 years |  |  |  |  |

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