Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net income available to common shareholders	$ 126.9	$ 111.1
Dividends paid on and undistributed earnings allocated to participating securities	0.0	0.0
Earnings attributable to common shareholders	$ 126.9	$ 111.1
Weighted average common shares outstanding for basic EPS (in shares)	427.2	370.7
Effect of dilutive equity-based awards (in shares)	2.6	3.4
Weighted average common shares and common-equivalent shares for diluted EPS (in shares)	429.8	374.1
EPS:
Basic (USD per share)	$ 0.30	$ 0.30
Diluted (USD per share)	$ 0.30	$ 0.30
Anti-dilutive equity-based awards excluded from calculation of diluted EPS (in shares)	12.9	7.2