Income Taxes - Provision for Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current Tax Provision:
Federal	$ 347.3	$ 495.8	$ 489.8
State	38.3	65.3	64.5
Non-U.S.	125.4	99.3	83.1
Total	511.0	660.4	637.4
Deferred Tax Provision:
Federal	(96.4)	(159.0)	(131.1)
State	24.6	(18.9)	(13.6)
Non-U.S.	(4.3)	2.1	(1.5)
Total	(76.1)	(175.8)	(146.2)
Provision for Income Taxes	$ 434.9	$ 484.6	$ 491.2