Reportable Segments (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Jan. 01, 2012	Jan. 02, 2011
Revenue by client sector
Revenue	$ 682,627	$ 611,124
International
Revenue by client sector
Revenue	159,931	126,557
U.S. commercial
Revenue by client sector
Revenue	177,430	135,135
U.S. federal government
Revenue by client sector
Threshold percentage for disclosure of revenue from a single client	10.00%
Revenue	271,408	283,520
U.S. state and local government
Revenue by client sector
Revenue	$ 73,858	$ 65,912

Aggregate revenue during the period from services rendered in the normal course of business, after deducting allowances and discounts.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 5

-Section 03

-Paragraph 1

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(d))

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Name:	us-gaap_SalesRevenueServicesNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration