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Goodwill and Intangible Assets - Narrative (Details) - USD ($) |  | 3 Months Ended | 9 Months Ended
--- | --- | --- | ---
Jul. 01, 2019 | Jun. 28, 2020 | Sep. 29, 2019 | Jun. 30, 2019 | Jun. 28, 2020 | Jun. 30, 2019
Goodwill [Line Items] |  |  |  |  |  |
Impairment of goodwill | $ 0 |  |  |  |  |
Goodwill |  | $ 958,162,000 | $ 924,820,000 |  | $ 958,162,000 |
Assets |  | 2,289,309,000 | 2,147,408,000 |  | 2,289,309,000 |
Amortization expense |  | 2,600,000 |  | $ 2,400,000 | $ 9,000,000.0 | $ 8,600,000
Income approach, discounted cash flow method |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |
Weighted rate used in fair value of goodwill (as a percent) |  |  |  |  | 70.00% |
Market approach |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |
Weighted rate used in fair value of goodwill (as a percent) |  |  |  |  | 30.00% |
RFS |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |
Impairment of goodwill |  |  | 7,800,000 |  |  |
Estimated fair values that exceeded their carrying values, percent (less than) | 30.00% |  |  |  |  |
Goodwill |  | 48,000,000 | 48,800,000 |  | $ 48,000,000 |
Assets |  |  | 61,000,000 |  |  |
ASP |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |
Estimated fair values that exceeded their carrying values, percent (less than) | 30.00% |  |  |  |  |
Goodwill |  | 109,000,000 |  |  | 109,000,000 |
GSG |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |
Gross amounts of goodwill |  | 492,200,000 | 459,500,000 |  | 492,200,000 |
Accumulated impairment |  | 17,700,000 | 17,700,000 |  | 17,700,000 |
Goodwill |  | 474,464,000 | 441,802,000 |  | 474,464,000 |
CIG |  |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |  |
Gross amounts of goodwill |  | 589,400,000 | 588,700,000 |  | 589,400,000 |
Accumulated impairment |  | 105,700,000 | 105,700,000 |  | 105,700,000 |
Goodwill |  | $ 483,698,000 | $ 483,018,000 |  | $ 483,698,000 |

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- Definition The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274 + Details
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