Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Summary of fair and carrying value of debt instruments
Credit facility, amount outstanding	$ 0	$ 0
Notes payable, Carrying Value	597.0	1,054.3
Debt instruments, Fair Value	666.3	1,155.3
Notes Payable to Fumedica [Member]
Summary of fair and carrying value of debt instruments
Notes payable, Fair Value	16.8	20.0
Notes payable, Carrying Value	15.3	17.9
6.0% Senior Notes due 2013 [Member]
Summary of fair and carrying value of debt instruments
Notes payable, Fair Value	0	453.7
Notes payable, Carrying Value	0	450.0
6.875% Senior Notes due 2018 [Member]
Summary of fair and carrying value of debt instruments
Notes payable, Fair Value	649.5	681.6
Notes payable, Carrying Value	$ 581.7	$ 586.4