Indebtedness (Details Textual)	12 Months Ended										12 Months Ended
	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2011 Note payable to Fumedica [Member] USD ($)	Dec. 31, 2011 Note payable to Fumedica [Member] CHF	Dec. 31, 2010 Note payable to Fumedica [Member] USD ($)	Dec. 31, 2010 Note payable to Fumedica [Member] CHF	Dec. 31, 2006 Note payable to Fumedica [Member] CHF	Dec. 31, 2011 6.0% Senior notes due 2013 [Member] USD ($)	Dec. 31, 2010 6.0% Senior notes due 2013 [Member] USD ($)	Mar. 04, 2008 6.0% Senior notes due 2013 [Member] USD ($)	Dec. 31, 2011 6.875% Senior notes due 2018 [Member] USD ($)	Dec. 31, 2010 6.875% Senior notes due 2018 [Member] USD ($)	Mar. 04, 2008 6.875% Senior notes due 2018 [Member] USD ($)	Dec. 31, 2011 New Cambridge Leases [Member] USD ($)
Debt Instrument [Line Items]
Principal amount senior notes										$ 450,000,000			$ 550,000,000
Redemption percentage par value of senior notes										99.886%			99.184%
Interest rate on Senior Notes										6.00%			6.875%
Increased carrying amount of interest rate swap											62,800,000
Notes payable, line of credit and other financing arrangements	1,060,808,000	1,066,379,000	16,400,000		18,700,000		61,400,000	449,900,000	449,800,000		592,300,000	597,900,000
Present value of notes payable			19,700,000	18,600,000	22,000,000	20,700,000
Remaining obligation of financing arrangements														2,200,000
Indebtedness (Textual) [Abstract]
Notes redemption condition	100% of the principal amount plus accrued interest and a specified make-whole amount
Percentage of redemption of notes	100.00%
Debt issuance costs	8,000,000
Interest to be amortized on debt	45,400,000
Senior unsecured revolving credit facility	360,000,000
Borrowings under revolving credit facility	$ 0	$ 0