Debt and Credit Facilities (Long-Term Debt Excluding Current Maturities) (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Long-term debt excluding current maturities	$ 4,492.6	$ 4,491.7
4.25% Senior notes due 2023 [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.25%	4.25%
Long-term debt excluding current maturities	$ 699.2	$ 699.1
Seven Point Two Zero Percent Debentures [Domain]
Long-term debt excluding current maturities	$ 22.4	$ 22.4
Three Point Five Five Percent Senior Notes due 2024 [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.55%	3.55%
Long-term debt excluding current maturities	$ 498.2	$ 498.0
6.48% Debentures Due 2025 [Member]
Debt Instrument, Interest Rate, Stated Percentage	6.48%	6.48%
Long-term debt excluding current maturities	$ 149.7	$ 149.7
Three Point Five Percent Senior notes Due Two Thousand Twenty Six [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.50%	3.50%
Long-term debt excluding current maturities	$ 398.0	$ 397.8
Three Point Seven Five Percent Senior Notes Due Two Thousand Twenty Eight [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.75%	3.75%
Long-term debt excluding current maturities	$ 546.3	$ 546.2
Three Point Eight Percent Senior Notes Due Two Thousand Twenty Nine [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.80%	3.80%
Long-term debt excluding current maturities	$ 745.2	$ 745.0
5.75% Senior notes due 2043 [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.75%	5.75%
Long-term debt excluding current maturities	$ 495.0	$ 495.0
Four Point Six Five Percent Senior Notes due Twenty Forty Four [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.65%	4.65%
Long-term debt excluding current maturities	$ 296.3	$ 296.3
Seven Point Two Zero Percent Debentures due Two Thousand Fourteen to Two Thousand Twenty Five [Member] [Member]
Debt Instrument, Interest Rate, Stated Percentage	7.20%	7.20%
Four Point Three Percent Senior Notes Due Two Thousand Forty Eight [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.30%	4.30%
Long-term debt excluding current maturities	$ 296.4	$ 296.3
Four Point Five Percent Senior Notes Due Two Thousand Forty Nine [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.50%	4.50%
Long-term debt excluding current maturities	$ 345.9	$ 345.9