Valuation and Qualifying Accounts (Details) (Allowance for Doubtful Accounts [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance for Doubtful Accounts, Balance at beginning of year	$ 48,125		$ 37,998		$ 39,674
Allowance for doubtful accounts, Charged to Income	12,452		12,957		5,001
Allowance for Doubtful Accounts, Other	3,262	[1]	5,357	[1]	5,849	[1]
Allowance for Doubtful Accounts, Write-down	9,601		8,187		12,526
Allowance for Doubtful Accounts, Balance at end of year	$ 54,238		$ 48,125		$ 37,998

[1] Represents the allowance for doubtful accounts of the businesses acquired by the company during 2012, 2011, and 2010.