Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Summary of fair and carrying value of debt instruments
Credit facility, amount outstanding	$ 0	$ 0
Total fair value	665.4	1,155.3
Notes Payable to Fumedica
Summary of fair and carrying value of debt instruments
Notes payable, fair value	17.5	20.0
6.0% Senior Notes due 2013
Summary of fair and carrying value of debt instruments
Notes payable, fair value	0	453.7
6.875% Senior Notes due 2018
Summary of fair and carrying value of debt instruments
Notes payable, fair value	$ 647.9	$ 681.6