Restructuring and Other Charges - Summary of Restructuring and Other Charges Impacts on Reportable Segment Income by Line of Business (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Apr. 01, 2022	Apr. 02, 2021	Apr. 01, 2022	Apr. 02, 2021
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			$ 14,929
Impairment of long-lived assets and equity method investment			74,585	$ 33,197
AWE Management Ltd
Restructuring Cost and Reserve [Line Items]
Gain on termination of lease			(7,100)
Impairment of long-lived assets and equity method investment		$ 33,200		33,200
People & Places Solutions
Restructuring Cost and Reserve [Line Items]
Real estate impairment and other transformation activities			71,000
CH2M HILL Companies, Ltd.
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 108,164	30,347	177,524	78,741
Loss related to settlement	91,300		91,300
CH2M HILL Companies, Ltd. | Operating profit (mainly SG&A)
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	110,171	25,052	188,075	45,544
CH2M HILL Companies, Ltd. | Other (Income) Expense, net
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	(2,007)	5,295	(10,551)	33,197
CH2M HILL Companies, Ltd. | Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	102,514	15,006	109,352	55,025
CH2M HILL Companies, Ltd. | Critical Mission Solutions | Operating Segments
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	3,462	710	4,616	3,919
CH2M HILL Companies, Ltd. | People & Places Solutions | Operating Segments
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	671	1,533	61,840	6,699
CH2M HILL Companies, Ltd. | PA Consulting | Operating Segments
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 1,517	$ 13,098	$ 1,716	$ 13,098