Acquisitions (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2010	May 31, 2012	Dec. 31, 2011		Dec. 31, 2009
Entity Number of Employees			40
Business Acquisition, Cost of Acquired Entity, Purchase Price			$ 18,800,000			$ 116,700,000
Business Acquisition, Percentage of Voting Interests Acquired			100.00%
Integration Merger And Acquisition Related Costs And Other Charges	2,400,000	7,900,000
Business Acquisition, Purchase Price Allocation, Goodwill Amount	7,500,000
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets	8,500,000			8,535,000	[1]
Business Acquisition, Cost of Acquired Entity, Cash Paid		$ 12,200,000				$ 104,500,000

[1] The Company acquired Ideas International in 2012 and recorded a total of $8.5 million of amortizable intangible assets. See Note 2-Acquisitions above for additional information.