Long-Term Debt (Long-Term Debt) (Details) (USD $) In Millions, unless otherwise specified																			9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 7% Senior Notes Due 2014 [Member]	Dec. 31, 2011 7% Senior Notes Due 2014 [Member]	Sep. 30, 2012 6.75% Senior Notes Due 2018 [Member]	Dec. 31, 2011 6.75% Senior Notes Due 2018 [Member]	Sep. 30, 2012 5.5% Senior Notes Due 2020 [Member]	Dec. 31, 2011 5.5% Senior Notes Due 2020 [Member]	Sep. 30, 2012 Term Loan Facility Due 2016 [Member]	Dec. 31, 2011 Term Loan Facility Due 2016 [Member]	Sep. 30, 2012 Revolving Credit Facility Due 2016 [Member]	Dec. 31, 2011 Revolving Credit Facility Due 2016 [Member]	Sep. 30, 2012 Mortgage Facility [Member]		Dec. 31, 2011 Mortgage Facility [Member]		Sep. 30, 2012 Capital Leases [Member]	Dec. 31, 2011 Capital Leases [Member]	Sep. 30, 2012 Secured Debt [Member] Mortgage Facility [Member]
Senior Notes			$ 0	$ 14.7	$ 395.5	$ 395.0	$ 350.0	$ 0
Term loan facility									500.0	500.0
Revolving credit facility, amount outstanding											395.0	495.0
Mortgage facility													205.4	[1]	211.5	[1]
Capital leases																	46.4	30.8
Debt and capital lease obligations	1,892.3	1,647.0
Less: current maturities	(28.2)	(12.6)
Long-term debt, net of current maturities	1,864.1	1,634.4
Monthly principal and interest payments on mortgage facility																			1.7
Balloon payment for mortgage																			$ 155.4

[1] The mortgage facility requires monthly principal and interest payments of $1.7 million based on a fixed amortization schedule with a balloon payment of $155.4 million due November 2017.