Accumulated Other Comprehensive Income - Changes in Components of Accumulated Other Comprehensive Income, Net of Tax (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Other Comprehensive Income Loss [Line Items]
Stockholders equity, beginning balance	$ 12,388.1
AOCI before reclassifications	(20.3)
Reclassifications to statements of earnings	(35.6)
Stockholders equity, ending balance	12,194.2
Foreign Currency Translation [Member]
Other Comprehensive Income Loss [Line Items]
Stockholders equity, beginning balance	(32.8)
AOCI before reclassifications	25.6
Stockholders equity, ending balance	(7.2)
Defined Benefit Plan Items [Member]
Other Comprehensive Income Loss [Line Items]
Stockholders equity, beginning balance	(225.5)
AOCI before reclassifications	(12.4)
Reclassifications to statements of earnings	2.9
Stockholders equity, ending balance	(235.0)
Total AOCI [Member]
Other Comprehensive Income Loss [Line Items]
Stockholders equity, beginning balance	(241.9)
Stockholders equity, ending balance	(297.8)
Cash Flow Hedges [Member]
Other Comprehensive Income Loss [Line Items]
Stockholders equity, beginning balance	16.4
AOCI before reclassifications	(33.5)
Reclassifications to statements of earnings	(38.5)
Stockholders equity, ending balance	$ (55.6)