Long-term Debt (Details) (USD $) In Millions, unless otherwise specified								6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Senior Subordinated Convertible Notes [Member]	Jun. 30, 2012 Mortgages [Member]	Dec. 31, 2011 Mortgages [Member]	Jun. 30, 2012 Capital Lease Obligations [Member]	Dec. 31, 2011 Capital Lease Obligations [Member]	Jun. 30, 2012 Mortgages [Member]	Jun. 30, 2012 8.375% Senior Subordinated Notes due 2020 Senior Subordinated Notes [Member]	Dec. 31, 2011 8.375% Senior Subordinated Notes due 2020 Senior Subordinated Notes [Member]	Jun. 30, 2012 7.625% Senior Subordinated Notes due 2017 Senior Subordinated Notes [Member]	Dec. 31, 2011 7.625% Senior Subordinated Notes due 2017 Senior Subordinated Notes [Member]	Jun. 30, 2012 3% Senior Subordinated Convertible Notes due 2012 Senior Subordinated Convertible Notes [Member]	Dec. 31, 2011 3% Senior Subordinated Convertible Notes due 2012 Senior Subordinated Convertible Notes [Member]
Debt Instrument [Line Items]
Stated interest rate of debt instrument			3.00%						8.375%	8.375%	7.625%	7.625%	3.00%	3.00%
Face value of debt instrument													$ 15.1	$ 15.1
Discount of debt instrument													0.1	0.4
Long-term debt, current and noncurrent	416.1	458.6		54.0	96.8	3.9	3.9		200.0	200.0	143.2	143.2	15.0	14.7
Less: current portion	(16.8)	(19.5)
Long-term debt	399.3	439.1
Repayment of mortgage notes payable								$ 41.0