Long-Term Debt - Long-Term Debt (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Total	$ 2,773.6	$ 3,120.4
Less: current maturities	(340.0)	(390.0)
Long-term debt	2,433.6	2,730.4
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Total	397.0	396.4
7% Debentures, Due 2025
Debt Instrument [Line Items]
Total	124.4	124.3
3.450% Senior Notes, Due 2027
Debt Instrument [Line Items]
Total	297.3	296.9
3.500% Senior Notes, Due 2027
Debt Instrument [Line Items]
Total	495.3	494.8
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Total	228.1	228.1
4.250% Senior Notes, Due 2047
Debt Instrument [Line Items]
Total	591.7	591.5
Floating Rate Senior Notes, Due 2020
Debt Instrument [Line Items]
Total	299.7	299.0
Floating Rate Senior Notes, Due 2019
Debt Instrument [Line Items]
Total		299.2
Trade Receivable Facility
Debt Instrument [Line Items]
Total	340.0	390.0
Other Notes
Debt Instrument [Line Items]
Total	$ 0.1	$ 0.2

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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