Income Taxes - Reconciliation between Provision for Income Taxes at Statutory Rate and Provision for Income Taxes at Effective Tax Rate (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Tax expense at United States statutory rate	$ 127.7	$ 170.2	$ 147.4
Increase (decrease) in tax resulting from:
Differences between U.S. and foreign tax rates on foreign income, including withholding taxes	(16.6)	203.1	(60.0)
U.S. tax (benefit) on foreign income net of foreign tax credits	(10.2)	(23.9)	(73.4)
(Decrease) increase in valuation allowances	(5.6)	(205.6)	85.7
State taxes, net of federal benefit	0.3	1.7	4.1
Unrecognized tax benefits	5.3	10.1	13.0
Other	3.8	(8.3)	(4.2)
Total	$ 104.7	$ 147.3	$ 112.6