CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Sep. 29, 2023	Sep. 30, 2022	Oct. 01, 2021
Statement of Comprehensive Income [Abstract]
Net Earnings of the Group	$ 719,656	$ 715,412	$ 430,829
Other Comprehensive Income (Loss):
Foreign currency translation adjustment	148,971	(397,819)	15,585
Change in cash flow hedges	(20,500)	154,541	29,332
Change in pension plan liabilities	(16,389)	92,527	142,135
Other comprehensive income (loss) before taxes	112,082	(150,751)	187,052
Income Tax Benefit (Expense):
Foreign currency translation adjustment	1,132	19,019	(3,110)
Cash flow hedges	5,870	(43,595)	(7,357)
Change in pension plan liabilities	(1,908)	(5,361)	(37,970)
Income Tax Benefit (Expense):	5,094	(29,937)	(48,437)
Net other comprehensive income (loss)	117,176	(180,688)	138,615
Net Comprehensive Income of the Group	836,832	534,724	569,444
Net Earnings Attributable to Noncontrolling Interests	(32,265)	(36,788)	(39,213)
Net (Earnings) Loss Attributable to Redeemable Noncontrolling Interests	(21,614)	(34,585)	85,414
Net Comprehensive Income Attributable to Jacobs	$ 782,953	$ 463,351	$ 615,645