Income Taxes - Provision/Benefit for Income Taxes and Income Taxes Paid (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal	$ (46.2)	$ 438.5	$ 134.2
State	24.4	2.4	12.4
Foreign	116.6	(13.7)	101.6
Current, Total	94.8	427.2	248.2
Deferred:
Federal	37.9	(1,728.5)	(108.5)
State	(8.8)	(95.5)	2.3
Foreign	(15.7)	48.0	(47.0)
Deferred, Total	13.4	(1,776.0)	(153.2)
Provision (benefit) for income taxes	108.2	(1,348.8)	95.0
Net income taxes paid	$ 237.1	$ 266.9	$ 269.6