Income Taxes - Schedule of Provision for Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal	$ 8.6	$ 121.4	$ 272.1
State	10.6	31.0	21.4
Foreign	42.0	203.5	168.5
Total current	61.2	355.9	462.0
Deferred:
Federal	(354.5)	(1,035.3)	(1,733.3)
State	(63.2)	(283.3)	28.5
Foreign	(650.2)	(266.7)	(77.0)
Total deferred	(1,067.9)	(1,585.3)	(1,781.8)
Total income tax benefit	(1,006.7)	(1,229.4)	(1,319.8)
Total income tax provision - discontinued operations	31.0	129.5	195.2
Total income tax benefit - continuing operations	$ (1,037.7)	$ (1,358.9)	$ (1,515.0)