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Description of Business and Basis of Presentation (Details) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 30, 2018 Business | Mar. 27, 2015 Business | Sep. 28, 2018 segment | Sep. 29, 2017 | Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract] |  |  |  |  |
Cost-reimbursable |  |  | 76.00% | 81.00% | 82.00%
Fixed-price |  |  | 24.00% | 19.00% | 18.00%
Number of operating and reporting structure of business | 3 | 4 | 3 |  |

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