Stock-Based Compensation - Narrative (Details) - USD ($)	12 Months Ended
	Oct. 03, 2025	Sep. 27, 2024	Sep. 29, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance	15,900,000
Vesting of stock-awards in connection with the transaction	$ 13,000,000
Compensation expense	21,000,000	$ 18,000,000	$ 3,000,000
Income tax benefits recognized from stock-based compensation	3,000,000	0	0
RSUs
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized compensation expense	$ 27,000,000
Share-based compensation, weighted average period	2 years
Vested fair value	$ 1,000,000	0	0
RSUs | CMS
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Awards granted in the period (in shares)	342,741
RSUs | Jacobs Solutions Inc.
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Non-vested awards outstanding (in shares)	65,182
RSUs | Tranche One
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting rights, percentage	50.00%
Award vesting period	2 years
RSUs | Tranche Two
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting rights, percentage	33.00%
Award vesting period	3 years
RSUs | Tranche Three
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting rights, percentage	25.00%
Award vesting period	4 years
RSUs | Share-Based Compensation Award, Subject To Cliff Vesting
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting period	3 years
Stock Options
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting period	3 years
Performance Shares, Including Two-Year Market Condition
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized compensation expense	$ 10,000,000
Share-based compensation, weighted average period	2 years
Employee Stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance	2,500,000
Proceeds from stock plans	$ 3,000,000
Share-based compensation arrangement by share-based payment award, shares issued in period (in shares)	100,000
Sale of stock, price per share (in dollars per share)	$ 22.75
Employee Stock | Employee Stock Purchase Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, discount percentage	5.00%
Time Vested Class B Units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting rights, percentage	20.00%
Award vesting period	5 years
Class B Units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Unrecognized compensation expense	$ 0
Compensation expense		18,000,000	3,000,000
Income tax benefits recognized from stock-based compensation	$ 0	$ 0	$ 0
Performance Stock Options | Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting period	1 year
Performance Stock Options | Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting period	3 years