CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Sep. 26, 2025	Sep. 27, 2024	Sep. 29, 2023
Statement of Comprehensive Income [Abstract]
Net Earnings of the Group	$ 303,956	$ 852,643	$ 719,656
Other Comprehensive (Loss) Income:
Foreign currency translation adjustment	(10,110)	266,421	148,971
Change in cash flow hedges	(6,284)	(84,193)	(20,500)
Change in pension plan liabilities	(2,717)	(50,404)	(16,389)
Other comprehensive (loss) income before taxes	(19,111)	131,824	112,082
Income Tax Benefit (Expense):
Foreign currency translation adjustment	5,657	0	1,132
Cash flow hedges	1,750	21,521	5,870
Change in pension plan liabilities	744	5,159	(1,908)
Income Tax Benefit:	8,151	26,680	5,094
Net other comprehensive (loss) income	(10,960)	158,504	117,176
Net Comprehensive Income of the Group	292,996	1,011,147	836,832
Net Earnings Attributable to Noncontrolling Interests	(3,443)	(31,551)	(32,265)
Net Earnings Attributable to Redeemable Noncontrolling Interests	(11,177)	(14,999)	(21,614)
Net Comprehensive Income Attributable to Jacobs	$ 278,376	$ 964,597	$ 782,953