CONSOLIDATED STATEMENTS OF EARNINGS - USD ($) $ in Thousands	12 Months Ended
	Sep. 26, 2025	Sep. 27, 2024	Sep. 29, 2023
Income Statement [Abstract]
Revenues	$ 12,029,783	$ 11,500,941	$ 10,851,420
Direct cost of contracts	(9,044,849)	(8,668,185)	(8,140,560)
Gross profit	2,984,934	2,832,756	2,710,860
Selling, general and administrative expenses	(2,121,300)	(2,140,320)	(2,034,376)
Operating Profit	863,634	692,436	676,484
Other Income (Expense):
Interest income	35,804	34,454	24,975
Interest expense	(145,788)	(169,058)	(168,085)
Loss on extinguishment of debt	(20,510)	0	0
Miscellaneous (expense) income, net	(189,663)	219,454	(12,399)
Total other (expense) income, net	(320,157)	84,850	(155,509)
Earnings from Continuing Operations Before Taxes	543,477	777,286	520,975
Income Tax Expense for Continuing Operations	(215,555)	(131,493)	(101,336)
Net Earnings of the Group from Continuing Operations	327,922	645,793	419,639
Net (Loss) Earnings of the Group from Discontinued Operations, net of tax	(23,966)	206,850	300,017
Net Earnings of the Group	303,956	852,643	719,656
Net Earnings Attributable to Noncontrolling Interests from Continuing Operations	(3,443)	(17,990)	(18,900)
Net Earnings Attributable to Redeemable Noncontrolling Interests	(11,177)	(14,999)	(21,614)
Net Earnings Attributable to Jacobs from Continuing Operations	313,302	612,804	379,125
Net Earnings Attributable to Noncontrolling Interests from Discontinued Operations	0	(13,561)	(13,365)
Net (Loss) Earnings Attributable to Jacobs from Discontinued Operations	(23,966)	193,289	286,652
Net Earnings Attributable to Jacobs	$ 289,336	$ 806,093	$ 665,777
Net Earnings Per Share:
Basic Net Earnings from Continuing Operations Per Share (in dollars per share)	$ 2.59	$ 4.81	$ 3.06
Basic Net Earnings from Discontinued Operations Per Share (in dollars per share)	(0.20)	1.54	2.26
Basic Earnings Per Share (in dollars per share)	2.39	6.35	5.32
Diluted Net Earnings from Continuing Operations Per Share (in dollars per share)	2.58	4.79	3.05
Diluted Net Earnings from Discontinued Operations Per Share (in dollars per share)	(0.20)	1.54	2.25
Diluted Earnings Per Share (in dollars per share)	$ 2.38	$ 6.32	$ 5.30