Income Taxes - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
	Jun. 18, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Contingency [Line Items]
Effective income tax rate		39.10%	15.40%	42.10%	15.80%
Income tax expense (benefit), impairment of intangible assets		$ (202.0)	$ (1,100.0)
Income tax expense (benefit), expiration of uncertain tax positions		(73.5)
Income tax expense (benefit), federal return to provision adjustments		$ (29.0)
Income tax expense (benefit), change in tax status of various non-U.S. jurisdictions				$ (10.1)
Income tax expense (benefit), excess book deductions for equity-based compensation				(14.4)
Income tax expense (benefit), excess book deductions for equity based compensation				14.7
Income tax expense (benefit), interest related to uncertain tax liabilities				12.7
Income tax expense (benefit), reduction of certain income tax contingencies			$ (67.9)
Income tax expense (benefit), reduction in valuation allowance					$ (69.4)
Interest related to uncertain tax liabilities					$ 9.0
Swiss Federal Tax Administration
Income Tax Contingency [Line Items]
Income tax expense (benefit), withholding tax refund received from Switzerland				$ (13.2)
Minimum | Internal Revenue Service | 2018 Tax Year
Income Tax Contingency [Line Items]
Unrecognized income tax expense due to change in tax regulations	$ 180.0
Maximum | Internal Revenue Service | 2018 Tax Year
Income Tax Contingency [Line Items]
Unrecognized income tax expense due to change in tax regulations	$ 220.0