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Revenue and Contract Balances - Narrative (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Jun. 27, 2021 | Mar. 29, 2020 | Jun. 27, 2021 | Jun. 28, 2020 | Sep. 27, 2020
Disaggregation of Revenue [Line Items] |  |  |  |  |
Contract liability revenue recognized during the period |  |  | $ 108,000 | $ 106,000 |
Net favorable (unfavorable) operating income adjustments | $ 1,700 | $ (2,800) | 2,800 | (2,800) |
Liabilities for anticipated losses | 8,000 |  | 8,000 |  | $ 13,200
Estimated cost to complete the related contracts | 81,000 |  | $ 81,000 |  | 118,000
Period for billing and collecting unbilled receivables |  |  | 12 months |  |
Decline in allowance for doubtful accounts |  |  | $ 3,800 |  |
Unbilled accounts receivable related to claims and requests for equitable adjustment on contracts | 11,000 |  | 11,000 |  | $ 11,000
Remaining unsatisfied performance obligation | $ 3,231,133 |  | $ 3,231,133 |  |
Remaining performance obligation, termination notice period one |  |  | 30 days |  |
Remaining performance obligation, termination notice period two |  |  | 60 days |  |
Remaining performance obligation, termination notice period three |  |  | 90 days |  |
CIG |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Gains (losses) due to change in contract value |  |  | $ 2,800 | $ (4,400) |

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