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Commitments and Contingencies (Details)	1 Months Ended	3 Months Ended
Commitments and Contingencies (Details)	Aug. 31, 2017 USD ($)	Dec. 27, 2019 USD ($)	Sep. 27, 2019 USD ($)	Mar. 27, 2020 USD ($)	Aug. 31, 2013 case	Sep. 28, 2012
UGL Infrastructure Pty Limited
Loss Contingencies [Line Items]
Percentage of ownership interest in joint venture						50.00%
NPMC
Loss Contingencies [Line Items]
Settlement payment			$ 130,000,000.0
Reduction of selling, general and administrative expenses in discontinued operations		$ 50,000,000.0
General Electric and GE Electrical International Inc \| Pending Litigation \| Minimum
Loss Contingencies [Line Items]
Damages sought	$ 530,000,000.0
JKC Australia LNG Pty Limited \| Pending Litigation
Loss Contingencies [Line Items]
Damages sought	$ 1,700,000,000
Kingston Power Plant of the TVA, Primary Case Greg Adkisson, ET AL v. Jacobs Engineering Group Inc.
Loss Contingencies [Line Items]
Number of pending claims \| case					6
Kingston Power Plant of the TVA, Secondary Case No. 3:13CV-505-TAV-HBG
Loss Contingencies [Line Items]
Number of pending claims \| case					10
LOCs
Loss Contingencies [Line Items]
Debt issued and outstanding			262,200,000	$ 262,800,000
Surety Bond
Loss Contingencies [Line Items]
Debt issued and outstanding			$ 2,000,000,000.0	$ 1,970,000,000