Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 29, 2019	Mar. 30, 2018	Mar. 29, 2019	Mar. 30, 2018
Statement of Comprehensive Income [Abstract]
Net Earnings of the Group	$ 62,773	$ 51,932	$ 192,363	$ 54,493
Other Comprehensive Income (Loss):
Foreign currency translation adjustment	31,352	9,714	(21,048)	27,694
Gain (loss) on cash flow hedges	348	179	2,138	1,061
Change in pension and retiree medical plan liabilities	(43,835)	2,594	(42,010)	8,866
Other comprehensive income (loss) before taxes	(12,135)	12,487	(60,920)	37,621
Income Tax (Expense) Benefit:
Cash flow hedges	10	(149)	(533)	(149)
Change in pension and retiree medical plan liabilities	8,417	(418)	7,896	(1,022)
Income Tax (Expense) Benefit:	8,427	(567)	7,363	(1,171)
Net other comprehensive income (loss)	(3,708)	11,920	(53,557)	36,450
Net Comprehensive Income (Loss) of the Group	59,065	63,852	138,806	90,943
Net (Earnings) Loss Attributable to Noncontrolling Interests	(5,856)	(3,345)	(11,150)	(3,743)
Net Comprehensive Income (Loss) Attributable to Jacobs	$ 53,209	$ 60,507	$ 127,656	$ 87,200