Financing (Details) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Long-term debt
Total debt	$ 4,088.5	$ 2,493.8
Less current maturities	999.8	0.1
Long-term debt	3,088.7	2,493.7
3.125% senior notes due 2016, net of unamortized discount [Member]
Long-term debt
Total debt	1,494.1	0
5.25% senior notes due 2012, net of unamortized discount [Member]
Long-term debt
Total debt	999.7	999.6
6.25% senior notes due 2014, net of unamortized discount [Member]
Long-term debt
Total debt	997.3	996.9
7.25% senior notes due 2019, net of unamortized discount [Member]
Long-term debt
Total debt	497.2	497.1
Revolving credit facility due August 13, 2013 [Member]
Long-term debt
Total debt	100.0	0
Other [Member]
Long-term debt
Total debt	$ 0.2	$ 0.2