Consolidated Statements of Earnings - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 30, 2018	Mar. 31, 2017	Mar. 30, 2018	Mar. 31, 2017
Income Statement [Abstract]
Revenues	$ 3,935,028	$ 2,302,567	$ 6,685,338	$ 4,854,171
Direct cost of contracts	(3,161,663)	(1,883,283)	(5,424,794)	(4,015,575)
Gross profit	773,365	419,284	1,260,544	838,596
Selling, general and administrative expenses	(627,079)	(351,111)	(1,066,615)	(681,795)
Operating Profit	146,286	68,173	193,929	156,801
Other Income (Expense):
Interest income	1,785	2,088	5,619	3,574
Interest expense	(19,228)	(3,755)	(26,319)	(7,273)
Miscellaneous income (expense), net	(6,676)	(6,015)	(9,146)	(6,731)
Total other (expense) income, net	(24,119)	(7,682)	(29,846)	(10,430)
Earnings Before Taxes	122,167	60,491	164,083	146,371
Income Tax Expense	(70,235)	(16,326)	(109,590)	(41,053)
Net Earnings of the Group	51,932	44,165	54,493	105,318
Net (Earnings) Loss Attributable to Noncontrolling Interests	(3,345)	5,853	(3,743)	5,236
Net Earnings Attributable to Jacobs	$ 48,587	$ 50,018	$ 50,750	$ 110,554
Net Earnings Per Share:
Basic (in dollars per share)	$ 0.34	$ 0.41	$ 0.38	$ 0.91
Diluted (in dollars per share)	$ 0.34	$ 0.41	$ 0.38	$ 0.91