Valuation and Qualifying Accounts (Details) (Allowance for Doubtful Accounts [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		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	$ 64,129		$ 54,238				$ 48,125
Allowance for doubtful accounts, Charged to Income	656		9,201		12,452
Allowance for Doubtful Accounts, Other	682	[1]	8,098	[1]	3,262	[1]
Allowance for Doubtful Accounts, Write-down	6,279		7,408		9,601
Allowance for Doubtful Accounts, Balance at end of year	$ 59,188		$ 64,129		$ 54,238		$ 48,125

[1] Represents the allowance for doubtful accounts of the businesses acquired by the company during 2014, 2013, and 2012.