Long-Term Obligations (Long-Term Obligations) (Details) (USD $)	Sep. 30, 2011	Dec. 31, 2010
Eurodollar loans under five-year revolving credit agreement bearing annual interest equal to the British Bankers Association LIBOR Rate ("BBA LIBOR") plus an applicable margin based on the Company's consolidated leverage ratio (consolidated funded indebtedness to consolidated EBITDA)	$ 80,000,000	$ 0
Other long-term obligations	2,111,000	4,497,000
Unsecured acquisition obligations and contingent consideration, net of imputed interest, payable in various installments through 2014	35,822,000	619,000
Total long-term obligations	622,452,000	494,890,000
Less: current installments	104,710,000	619,000
Long-term obligations, excluding current installments	517,742,000	494,271,000
Convertible debt, fixed interest rate	2.75%
Option 2012 [Member]
Convertible debentures to mature in 2037, bearing fixed interest of 2.75%, with a put/call option	275,000,000	275,000,000
Unamortized discount	(11,678,000)	(19,273,000)
Convertible debt, fixed interest rate	2.75%	2.75%
Option 2014 [Member]
Convertible debentures to mature in 2037, bearing fixed interest of 2.75%, with a put/call option	275,000,000	275,000,000
Unamortized discount	$ (33,803,000)	$ (40,953,000)
Convertible debt, fixed interest rate	2.75%	2.75%