Fair Value of Financial Instruments (Details) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Goodwill, Impairment Loss	$ 123,600,000	$ 99,501,000	$ 21,310,000
Goodwill	1,291,231,000	1,291,231,000	1,237,607,000	1,330,917,000
Carrying value and fair value of long-term debt
Variable-rate long-term debt, Carrying Value	592,422,000	592,422,000		556,914,000
Variable-rate long-term debt, Fair Value	592,422,000	592,422,000		556,914,000
Vetstreet [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset Impairment Charges		22,900,000
Goodwill, Impairment Loss		99,500,000
Goodwill	8,800,000	8,800,000
Long-Lived Assets	$ 28,700,000	$ 28,700,000