Earnings Per Share - Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Computation Of Earnings Per Share Line Items
Net income	$ 125.4	$ 141.0	$ 476.9	$ 391.2
Net income from continuing operations	$ 127.1	$ 117.5	$ 276.1	$ 342.0
Weighted average common shares outstanding
Basic (shares)	181.5	181.4	181.7	181.1
Dilutive impact of stock options, restricted stock units and performance share units	2.0	2.2	2.0	1.9
Diluted (shares)	183.5	183.6	183.7	183.0
Earnings (loss) Per Share, Basic
Continuing operations (in dollars per share)	$ 0.70	$ 0.65	$ 1.52	$ 1.89
Discontinued operations (in dollars per share)	(0.01)	0.13	1.10	0.27
Basic earnings (loss) per ordinary share (in dollars per share)	0.69	0.78	2.62	2.16
Earnings (loss) Per Share, Diluted
Continuing operations (in dollars per share)	0.69	0.64	1.50	1.87
Discontinued operations (in dollars per share)	(0.01)	0.13	1.10	0.27
Diluted earnings (loss) per ordinary share (in dollars per share)	$ 0.68	$ 0.77	$ 2.60	$ 2.14
Anti-dilutive stock options excluded from the calculation of diluted earnings per share	1.6	0.0	1.8	1.8