Share-Based Compensation (Tables)

6 Months Ended

Mar. 31, 2019

Disclosure of Compensation Related Costs, Share-based Payments [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
	2019			2018			2019			2018
Before-tax share-based compensation cost		$11.9			$10.7			$21.2			$22.5
Income tax benefit	(2.8		)	(2.1		)	(5.0		)	(5.3		)
After-tax share-based compensation cost		$9.1			$8.6			$16.2			$17.2

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	17.5	%
Risk-free interest rate	2.8	%
Expected dividend yield	2.6	%