Business and Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2012

Property, Plant and Equipment [Table Text Block]

Property, equipment and leasehold improvements, less accumulated depreciation and amortization, consist of the following (in thousands):

	Useful Life		December 31,
	(Years)		2012			2011
	Minimum	Maximum
Computer equipment and software	2	7	$	135,167		$	130,733
Furniture and equipment	3	8		29,907			34,828
Leasehold improvements	2	15		64,346			63,773
				229,420			229,334
Less — accumulated depreciation and amortization				(140,331	)		(161,202	)
			$	89,089		$	68,132

Schedule of Finite-Lived Intangible Assets [Table Text Block]

Changes in intangible assets subject to amortization during the two year period ended December 31, 2012 are as follows (in thousands):

December 31, 2012	Trade Name			Customer Relationships			Content			Software			Total
Gross cost, December 31, 2011	$	5,758		$	7,210		$	—		$	—		$	12,968
Additions due to acquisition (1)		240			3,170			3,170			1,955			8,535
Foreign currency translation impact		21			182			277			169			649
Gross cost		6,019			10,562			3,447			2,124			22,152
Accumulated amortization (2)		(3,531	)		(5,896	)		(497	)		(407	)		(10,331	)
Balance, December 31, 2012	$	2,488		$	4,666		$	2,950		$	1,717		$	11,821

December 31, 2011	Trade Name			Customer Relationships			Content		Software		Total
Gross cost, December 31, 2010	$	5,758		$	7,210		$	—	$	—	$	12,968
Foreign currency translation impact		—			—			—		—		—
Gross cost		5,758			7,210			—		—		12,968
Accumulated amortization (2)		(2,303	)		(3,605	)		—		—		(5,908	)
Balance, December 31, 2011	$	3,455		$	3,605		$	—	$	—	$	7,060

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

The estimated future amortization expense by year from amortizable intangibles is as follows (in thousands):

2013	$	5,490
2014		3,615
2015		2,005
2016		711
	$	11,821

Schedule of Intangible Assets and Goodwill [Table Text Block]

The following table presents changes to the carrying amount of goodwill by reporting unit during the two year period ended December 31, 2012 (in thousands):

	Research			Consulting			Events			Total
Balance, December 31, 2010 (1)	$	368,521		$	99,817		$	41,927		$	510,265
Foreign currency translation adjustments		(1,541	)		(140	)		(34	)		(1,715	)
Balance, December 31, 2011	$	366,980		$	99,677		$	41,893		$	508,550
Addition due to acquisition (2)		7,455			—			—			7,455
Foreign currency translation adjustments		2,790			672			39			3,501
Balance, December 31, 2012	$	377,225		$	100,349		$	41,932		$	519,506