Schedule of Valuation And Qualifying Accounts (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Valuation and Qualifying Accounts Disclosure [Line Items]
Provision for doubtful accounts	$ 21,728,000		$ 13,708,000		$ 19,214,000
Allowance for Doubtful Accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	17,400,000		21,000,000		26,400,000
Provision for doubtful accounts	21,700,000	[1]	13,700,000	[1]	19,200,000	[1]
Write-Offs	(18,100,000)		(17,300,000)		(24,600,000)
Balance at End of Year	21,000,000		17,400,000		21,000,000
Estimated Revenue Adjustments
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	6,800,000		6,500,000		8,700,000
Write-Offs	(11,000,000)		(11,800,000)		(9,200,000)
Balance at End of Year	6,400,000		6,800,000		6,500,000
Provision for Estimated Revenue Adjustments	$ 10,600,000	[2]	$ 12,100,000	[2]	$ 7,000,000	[2]

[1] Includes $0.1 million, $0.2 million and $0.5 million from discontinued operations for the years ended December 31, 2012, 2011 and 2010, respectively.

[2] Includes $0.2 million, $0.3 million and $0.5 million from discontinued operations for the years ended December 31, 2012, 2011 and 2010, respectively.