Goodwill and Intangibles (Details) (USD $)	9 Months Ended					9 Months Ended
	Jul. 01, 2012	Jul. 01, 2012 Engineering and consulting services (ECS)	Jul. 01, 2012 Technical support services (TSS)	Jul. 01, 2012 Engineering and architecture services (EAS)	Oct. 02, 2011 Engineering and architecture services (EAS)	Jul. 01, 2012 Remediation and construction management (RCM)
Goodwill
Balance at beginning of the period	$ 569,414,000	$ 405,678,000	$ 82,091,000	$ 17,710,000	$ 17,710,000	$ 63,935,000
Transfer out of segment		(29,338,000)				(16,097,000)
Transfer into segment			45,435,000
Goodwill additions	38,429,000	5,283,000	31,201,000			1,945,000
Currency translation adjustments	9,511,000	9,511,000
Goodwill adjustments	9,827,000	9,792,000	35,000
Balance at end of the period	627,181,000	400,926,000	158,762,000	17,710,000	17,710,000	49,783,000
Gross amount of goodwill				122,700,000	122,700,000
Accumulated impairment losses				$ 105,000,000	$ 105,000,000