Income Taxes - (Benefit)/Provision for Income Taxes and Income Taxes Paid (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal	$ 65.5	$ (46.2)	$ 438.5
State	9.8	24.4	2.4
Foreign	237.7	116.6	(13.7)
Current, Total	313.0	94.8	427.2
Deferred:
Federal	(90.2)	37.9	(1,728.5)
State	(4.2)	(8.8)	(95.5)
Foreign	(444.3)	(15.7)	48.0
Deferred, Total	(538.7)	13.4	(1,776.0)
(Benefit) provision for income taxes	(225.7)	108.2	(1,348.8)
Net income taxes paid	$ 192.5	$ 237.1	$ 266.9