Segment Information (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Segment Reporting Information [Line Items]
Revenues	$ 3,853.8	$ 4,019.6	$ 4,385.7
Technology [Member]
Segment Reporting Information [Line Items]
Intersegment profit	8.2	7.2	14.8
Revenues	595.5	672.9	724.7
Various Agencies Of U.S. Government [Member]
Segment Reporting Information [Line Items]
Revenues	$ 652.0	$ 842.0	$ 927.0

Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains.

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)

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

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