Segment Information (Detail) - Information About Reportable Segments (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenues	$ 374,406	$ 345,784	$ 1,141,059	$ 1,040,894
Gross contribution	222,431	203,626	684,300	613,773
Corporate and other expenses	(172,663)	(156,376)	(518,254)	(469,174)
Operating income	49,768	47,250	166,046	144,599
Research [Member]
Revenues	284,048	255,979	836,970	749,429
Gross contribution	193,540	173,615	571,547	506,420
Consulting And Product Support Services [Member]
Revenues	71,731	70,815	222,970	219,407
Gross contribution	24,380	24,458	79,886	78,820
Operating Segments [Member]
Revenues	18,627	18,990	81,119	72,058
Gross contribution	$ 4,511	$ 5,553	$ 32,867	$ 28,533

Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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- Definition

Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense.

+ References

No definition available.

+ Details

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- Definition

The net result for the period of deducting operating expenses from operating revenues.

+ References

No definition available.

+ Details

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- Definition

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.

+ References

Reference 1: 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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

+ Details

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