Goodwill and Intangible Assets (Detail) - Changes to Carrying Amount of Goodwill by Reporting Unit (Parentheticals) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Addition due to acquisition	$ 7,455	[1]
Research [Member]
Addition due to acquisition	7,455	[1]
Ideas International Limited [Member]
Addition due to acquisition	$ 7,500

[1] The Company acquired Ideas International in the second quarter of 2012 and recorded $7.5 million of goodwill. All of the recorded goodwill resulting from the acquisition has been included in the Research segment. See Note 2-Acquisition above for additional information.