Commitments and Contingencies (Details) (BPR Triax)	Apr. 17, 2012 item
BPR Triax
Loss contingencies
Number of former employees of BPR Triax charged with allegations of corruption	2

Represents the number of former employees charged with allegations of corruption under the Canadian Criminal Code.

No definition available.

Name:	ttek_NumberOfEmployeesChargedWithAllegationsOfCorruption
Namespace Prefix:	ttek_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant