Condensed Consolidated Balance Sheets (Unaudited) (Parentheticals) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Accumulated depreciation	$ 8,049.9	$ 8,106.8
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized	1,000,000,000	1,000,000,000
Common stock, issued	390,779,441	389,974,041
Common stock, outstanding	379,267,122	379,091,544
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, authorized	15,000,000	15,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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