Long-Term Debt - Long-Term Debt (Detail) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Total debt	$ 5,044.3	$ 5,100.9
Less: Current maturities	0.0	(0.1)
Long-term debt	5,044.3	5,100.8
0.650% Senior Notes, Due 2023
Debt Instrument [Line Items]
Total debt	698.3	697.4
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Total debt	398.6	398.3
7% Debentures, Due 2025
Debt Instrument [Line Items]
Total debt	124.6	124.6
3.450% Senior Notes, Due 2027
Debt Instrument [Line Items]
Total debt	298.1	297.9
3.500% Senior Notes, Due 2027
Debt Instrument [Line Items]
Total debt	496.7	496.4
2.500% Senior Notes, Due 2030
Debt Instrument [Line Items]
Total debt	471.8	491.1
2.400% Senior Notes, Due 2031
Debt Instrument [Line Items]
Total debt	888.2	891.8
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Total debt	228.3	228.3
4.250% Senior Notes, Due 2047
Debt Instrument [Line Items]
Total debt	590.1	592.1
3.200% Senior Notes, Due 2051
Debt Instrument [Line Items]
Total debt	849.6	882.9
Other Notes
Debt Instrument [Line Items]
Total debt	$ 0.0	$ 0.1