Goodwill and Intangibles (Details) (USD $)	12 Months Ended
	Oct. 02, 2011	Oct. 03, 2010
Goodwill
Net book value of acquired identifiable intangible assets	$ 81,100,000	$ 46,000,000
Balance at beginning of the period	394,422,000	319,685,000
Additions	160,662,000	56,411,000
Adjustments	17,816,000	12,893,000
Currency translation adjustments	(3,486,000)	5,433,000
Balance at end of the period	569,414,000	394,422,000
Engineering and consulting services (ECS)
Goodwill
Balance at beginning of the period	244,616,000	189,416,000
Additions	149,193,000	42,293,000
Adjustments	15,355,000	7,474,000
Currency translation adjustments	(3,486,000)	5,433,000
Balance at end of the period	405,678,000	244,616,000
Technical support services (TSS)
Goodwill
Balance at beginning of the period	68,661,000	57,256,000
Additions	11,469,000	10,226,000
Adjustments	1,961,000	1,179,000
Balance at end of the period	82,091,000	68,661,000
Engineering and architecture services (EAS)
Goodwill
Balance at beginning of the period	17,210,000	15,970,000
Adjustments	500,000	1,240,000
Balance at end of the period	17,710,000	17,210,000
Gross amount of goodwill	122,700,000	122,200,000
Accumulated impairment losses	105,000,000	105,000,000
Remediation and construction management (RCM)
Goodwill
Balance at beginning of the period		57,043,000
Additions		3,892,000
Adjustments		3,000,000
Balance at end of the period	$ 63,935,000	$ 63,935,000