Income Tax Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Federal Income Tax Note
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Change in Tax Rate, Deferred Tax Liability, Provisional Income Tax Benefit		$ 97.9
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Transition Tax for Accumulated Foreign Earnings, Provisional Income Tax Expense		66.4
Tax Cuts and Jobs Act of 2017, Complete Accounting, Transition Tax for Accumulated Foreign Earnings, Provisional Income Tax Expense	$ 11.5
Tax Cuts and Jobs Act of 2017, Complete Accounting, Undistributed Accumulated Earnings of Foreign Subsidiary for which Unrecognized Deferred Tax Liabilities Have Not Been Recorded	$ 700.0
Tax Cuts and Jobs Act of 2017, Accounting Complete	true
Additions to Tax Positions Taken During Prior Years	$ 261.5	0.3	$ 0.7
Valuation Allowance on Deferred Tax Assets	18.4	20.3
Income Taxes Paid, Net	139.7	$ 377.0	$ 384.3
U.S. Federal
Federal Income Tax Note
Operating Loss Carryforwards	$ 6.5
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2022
State and Local Jurisdiction
Federal Income Tax Note
Operating Loss Carryforwards	$ 195.0
Minimum | State and Local Jurisdiction
Federal Income Tax Note
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2019
Maximum | State and Local Jurisdiction
Federal Income Tax Note
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2038
Subsidiary Return | U.S. Federal
Federal Income Tax Note
Operating Loss Carryforwards	$ 0.7
Tax Year 2017
Federal Income Tax Note
Additions to Tax Positions Taken During Prior Years	$ 261.1