Long-Term Debt -Debt Balances and Interest Rates (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Revolving Loan [Member]		Dec. 31, 2012 Revolving Loan [Member]	Mar. 31, 2013 Term Loan [Member]		Dec. 31, 2012 Term Loan [Member]	Mar. 31, 2013 Senior Secured Notes, due 2018 [Member]		Dec. 31, 2012 Senior Secured Notes, due 2018 [Member]	Mar. 31, 2013 2019 Senior Notes, due 2019 [Member]		Dec. 31, 2012 2019 Senior Notes, due 2019 [Member]	Feb. 17, 2012 2019 Senior Notes, due 2019 [Member]	Mar. 31, 2013 Senior Subordinated Notes [Member]		Dec. 31, 2012 Senior Subordinated Notes [Member]	Mar. 31, 2013 Senior Notes, due 2015 [Member]		Dec. 31, 2012 Senior Notes, due 2015 [Member]	Dec. 31, 2011 Senior Notes, due 2015 [Member]
Debt Instrument [Line Items]
Debt, short-term and long-term			$ 0		$ 0	$ 1,299.5		$ 1,339.5	$ 500.0		$ 500.0	$ 1,305.0		$ 1,305.0		$ 571.5		$ 621.5	$ 0		$ 0	$ 129.0
Premium, unamortized												4.8		5.0	5.7
Debt, total short-term and long-term	3,680.8	3,771.0
Current maturities of long-term debt	0	(40.0)
Debt	$ 3,680.8	$ 3,731.0
Long-term Debt, weighted average interest rate			0.00%	[1]		3.90%	[1]		8.00%	[1]		8.50%	[1]			12.535%	[1]		0.00%	[1]

[1] Weighted-average interest rate at March 31, 2013