Consolidated Statements of Earnings - USD ($) $ in Thousands	12 Months Ended
	Sep. 29, 2017	Sep. 30, 2016	Oct. 02, 2015
Income Statement [Abstract]
Revenues	$ 10,022,788	$ 10,964,157	$ 12,114,832
Costs and Expenses:
Direct costs of contracts	(8,250,536)	(9,196,326)	(10,146,494)
Selling, general and administrative expenses	(1,379,983)	(1,429,233)	(1,522,811)
Operating Profit	392,269	338,598	445,527
Other Income (Expense):
Interest income	8,748	7,848	7,262
Interest expense	(12,035)	(15,260)	(19,503)
Gain/(Loss) on disposal of business and investments	10,880	(41,410)	(2,909)
Miscellaneous expense, net	(6,645)	(3,053)	(240)
Total other income (expense), net	948	(51,875)	(15,390)
Earnings Before Taxes	393,217	286,723	430,137
Income Tax Expense	(105,842)	(72,208)	(101,255)
Net Earnings of the Group	287,375	214,515	328,882
Net Loss (Earnings) Attributable to Noncontrolling Interests	6,352	(4,052)	(25,911)
Net Earnings Attributable to Jacobs	$ 293,727	$ 210,463	$ 302,971
Net Earnings Per Share:
Basic (in dollars per share)	$ 2.43	$ 1.75	$ 2.42
Diluted (in dollars per share)	$ 2.42	$ 1.73	$ 2.40