Operating Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Summary of reportable segments
Revenue	$ 68,511	$ 69,774	$ 217,864	$ 208,966
Direct Margin	45,180	46,641	142,940	137,705
Selling, marketing, administrative and other expenses	(37,424)	(36,213)	(117,895)	(112,244)
Amortization of intangible assets	(579)	(679)	(1,779)	(1,898)
Income from operations	7,177	9,749	23,266	23,563
Business Technology [Member]
Summary of reportable segments
Revenue	38,630	39,365	118,845	113,650
Direct Margin	25,645	26,556	78,687	75,965
Marketing and Strategy [Member]
Summary of reportable segments
Revenue	29,579	29,009	89,614	85,219
Direct Margin	20,261	19,675	61,012	57,137
Events [Member]
Summary of reportable segments
Revenue	302	1,400	9,405	10,097
Direct Margin	$ (726)	$ 410	$ 3,241	$ 4,603

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc.

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