Goodwill and Intangible Assets (Details) (USD $)	3 Months Ended	9 Months Ended			3 Months Ended	9 Months Ended			9 Months Ended	6 Months Ended	9 Months Ended
	Jun. 30, 2013	Jun. 29, 2014 item	Jun. 30, 2013	Jun. 29, 2014 Maximum [Member]	Jun. 30, 2013 Engineering and Consulting Services [Member]	Jun. 29, 2014 Engineering and Consulting Services [Member] item	Sep. 29, 2013 Engineering and Consulting Services [Member]	Jun. 29, 2014 Engineering and Consulting Services [Member] Maximum [Member]	Jun. 29, 2014 Technical Support Services [Member]	Mar. 31, 2013 Remediation and Construction Management [Member] item	Jun. 29, 2014 Remediation and Construction Management [Member] item	Jun. 29, 2014 Remediation and Construction Management [Member] Maximum [Member]
Goodwill
Balance at beginning of the period		$ 722,792,000				$ 353,608,000			$ 177,579,000		$ 191,605,000
Goodwill additions		11,472,000				11,472,000
Foreign exchange impact		(12,156,000)				(8,725,000)			51,000		(3,482,000)
Goodwill adjustments		475,000							161,000		314,000
Balance at end of the period		722,583,000				356,355,000			177,791,000		188,437,000
Gross amounts of goodwill						413,900,000	411,100,000
Accumulated impairment						57,500,000	57,500,000
Impairment of goodwill	56,600,000		56,600,000		56,600,000
Number of reporting units having fair value in excess of carrying value of less than 20%.		4				3					2
Goodwill		722,583,000				356,355,000			177,791,000		188,437,000
Represents the goodwill determined to have fair value in excess of carrying value of less than 20%						$ 214,000,000					$ 138,700,000
Number of reporting units recently acquired										2
Percentage of excess of fair value over carrying value				20.00%				20.00%				20.00%