Debt and Credit Facilities (Long-Term Debt Excluding Current Maturities) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Long-term debt excluding current maturities	$ 4,921.9	$ 3,740.7
Two Point Six Two Five Percent Senior Notes Due Two Thousand Twenty [Member]
Debt Instrument, Interest Rate, Stated Percentage	2.625%	2.625%
Long-term debt excluding current maturities	$ 0.0	$ 299.4
Two Point Nine Percent Senior Notes Due Two Thousand Twenty One [Member] [Member]
Long-term debt excluding current maturities	$ 298.9	$ 298.3
9.00% Debentures Due 2021 [Member]
Debt Instrument, Interest Rate, Stated Percentage	9.00%	9.00%
Long-term debt excluding current maturities	$ 124.9	$ 124.9
4.25% Senior notes due 2023 [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.25%	4.25%
Long-term debt excluding current maturities	$ 697.6	$ 697.1
Seven Point Two Zero Percent Debentures [Domain]
Long-term debt excluding current maturities	$ 37.3	$ 44.8
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	$ 496.4	$ 495.9
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]
Long-term debt excluding current maturities	396.7	0.0
Three Point Seven Five Percent Senior Notes Due Two Thousand Twenty Eight [Member]
Long-term debt excluding current maturities	544.9	544.5
Three Point Eight Percent Senior Notes Due Two Thousand Twenty Nine [Member]
Long-term debt excluding current maturities	$ 743.5	$ 0.0
5.75% Senior notes due 2043 [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.75%	5.75%
Long-term debt excluding current maturities	$ 494.4	$ 494.3
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	$ 295.9	$ 295.8
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]
Long-term debt excluding current maturities	$ 296.0	$ 295.9
Four Point Five Percent Senior Notes Due Two Thousand Forty Nine [Member]
Long-term debt excluding current maturities	345.5	0.0
Other Loans and Notes [Member]
Long-term debt excluding current maturities	$ 0.2	$ 0.1