Components of Provision for Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current provision:
Federal	$ 397.7	$ 322.9	$ 521.8
State	63.8	41.7	61.1
Foreign	210.5	213.2	205.4
Current Income Tax Expense (Benefit), Total	672.0	577.8	788.3
Deferred provision (benefit):
Federal	(173.8)	31.5	(57.8)
State	2.3	4.8	5.3
Foreign	(2.4)	(5.4)	(2.7)
Deferred taxes	(173.9)	30.9	(55.2)
Income taxes	$ 498.1	$ 608.7	$ 733.1