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Selected Quarterly Financial Data - Narrative (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 28, 2019 | Sep. 28, 2019 | Jun. 29, 2019 | Mar. 30, 2019 | Dec. 29, 2018 | Sep. 29, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 28, 2019 | Dec. 29, 2018 | Dec. 30, 2017
Acquisition related costs | $ 1,900 | $ 3,200 | $ 1,500 | $ 2,400 | $ 3,200 | $ 2,900 | $ 2,400 | $ 11,700 |  |  |
Restructuring, impairment and other costs | 2,100 | $ 2,500 | 5,700 |  |  |  |  |  | $ 13,033 | $ 12,583 |
Impairment charges | 4,200 |  | 200 | 2,800 |  |  |  |  | 322 | 2,218 | $ 0
Benefit for previously unrecognized tax benefits in respect of which the statute of limitation has expired | $ 3,300 |  |  |  | 1,500 |  |  |  | 2,758 | 1,257 |
Loss on sale of building |  |  | $ 400 |  |  |  |  |  |  |  |
Loss on disposal of a business |  |  |  | 2,600 |  |  |  |  |  |  |
Restructuring costs |  |  |  | 2,700 | 2,400 | 5,200 | 4,200 | 800 |  |  |
Gain related to acquisition of Monolith |  |  |  | $ 300 |  |  |  |  |  |  |
TCJA one-time charge |  |  |  |  | 3,200 |  |  |  |  |  |
Backlog amortization costs |  |  |  |  |  |  |  | 2,500 |  |  |
Purchase accounting inventory adjustments |  |  |  |  |  |  |  | 17,900 |  |  |
Stock compensation expense |  |  |  |  |  |  |  |  | 19,046 | 27,431 | 16,315
Selling, General and Administrative Expenses |  |  |  |  |  |  |  |  |  |  |
Acquisition related costs |  |  |  |  |  |  |  |  | 2,700 |  |
IXYS Corporation |  |  |  |  |  |  |  |  |  |  |
Acquisition related costs |  |  |  |  |  |  |  |  | 2,200 | 11,000 |
Backlog amortization costs |  |  |  |  | $ 3,700 | $ 3,100 | 3,100 |  |  |  |
Purchase accounting inventory adjustments |  |  |  |  |  |  | $ 19,000 |  |  |  |
IXYS Corporation | Selling, General and Administrative Expenses |  |  |  |  |  |  |  |  |  |  |
Stock compensation expense |  |  |  |  |  |  |  | $ 4,500 |  |  |
Other Segments | Selling, General and Administrative Expenses |  |  |  |  |  |  |  |  |  |  |
Acquisition related costs |  |  |  |  |  |  |  |  |  |  | $ 8,000
Other Segments | Operating Income (Loss) |  |  |  |  |  |  |  |  |  |  |
Acquisition related costs |  |  |  |  |  |  |  |  | $ 8,900 | 88,700 |
Impairment charges |  |  |  |  |  |  |  |  |  | 5,800 |
Backlog amortization costs |  |  |  |  |  |  |  |  |  | 12,400 |
Change in control expense |  |  |  |  |  |  |  |  |  | $ 2,100 |

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