Consolidated Statement Of Stockholders' Equity - USD ($) $ in Millions	Total	Common stock	Accumulated deficit	Accumulated deficit Cumulative Effect, Period of Adoption, Adjustment	Accumulated other comprehensive income (loss)	Additional Paid-in Capital [Member]
Other comprehensive income (loss), net of tax					$ 9.9
Common stock, dividends, per share, declared	$ 0.165
Balance at Sep. 30, 2020		$ 1.6	$ (714.2)		(24.7)	$ 1,378.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared						26.1
Stock-based compensation						6.3
Shares retained for employee taxes						1.0
Stock repurchased under buyback program						0.0
Stock issued under stock compensation plans	$ 0.0					1.5
Net income (loss)	$ 52.0
Balance at Jun. 30, 2021		1.6	(662.3)		(14.8)	1,358.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent				$ (0.1)
Other comprehensive income (loss), net of tax					4.9
Common stock, dividends, per share, declared	$ 0.055
Balance at Mar. 31, 2021		1.6	(676.7)		(19.7)	1,364.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared						8.7
Stock-based compensation						2.7
Shares retained for employee taxes						0.0
Stock repurchased under buyback program						0.0
Stock issued under stock compensation plans	$ 0.0					0.5
Net income (loss)	14.4
Balance at Jun. 30, 2021		1.6	(662.3)		(14.8)	1,358.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent	683.2			0.0
Common stock, value, issued	1.6
Other comprehensive income (loss), net of tax	$ (14.5)				(14.5)
Common stock, dividends, per share, declared	$ 0.174
Balance at Sep. 30, 2021	$ 694.9	1.6	(643.9)		(5.0)	1,342.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared						27.4
Stock-based compensation						6.6
Shares retained for employee taxes						1.9
Stock repurchased under buyback program						(25.0)
Stock issued under stock compensation plans	0.0					1.6
Net income (loss)	69.5
Balance at Jun. 30, 2022	$ 703.8	1.6	(574.4)		(19.5)
Other comprehensive income (loss), net of tax					(17.3)
Common stock, dividends, per share, declared	$ 0.058
Balance at Mar. 31, 2022		1.6	(600.9)		(2.2)	1,307.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared						9.1
Stock-based compensation						2.2
Shares retained for employee taxes						0.1
Stock repurchased under buyback program						(5.0)
Stock issued under stock compensation plans	$ 0.0					$ 0.5
Net income (loss)	26.5
Balance at Jun. 30, 2022	703.8	$ 1.6	$ (574.4)		$ (19.5)
Common stock, value, issued	1.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity Attributable to Parent	$ 703.8			$ 0.0