Share-Based Compensation (Tables)

6 Months Ended

Mar. 31, 2021

Share-based Payment Arrangement [Abstract]

Schedule of Recognized Share-Based Compensation Cost

Share-based compensation cost recognized on the consolidated income statements is summarized below:

	Three Months Ended		Six Months Ended
	31 March		31 March
	2021	2020	2021	2020
Before-tax share-based compensation cost	$12.9	$13.5	$22.4	$28.9
Income tax benefit	(3.1)	(3.1)	(5.4)	(6.8)
After-tax share-based compensation cost	$9.8	$10.4	$17.0	$22.1

Schedule of Assumptions for Fair Value of Market-Based Deferred Stock Units

The calculation of the fair value of market-based deferred stock units used the following assumptions:

Expected volatility	29.9	%
Risk-free interest rate	0.2	%
Expected dividend yield	2.1	%