Consolidated Statement Of Stockholders' Equity - USD ($) $ in Millions	Total	Common stock	Accumulated deficit	Accumulated other comprehensive income (loss)	Noncontrolling Interest [Member]	Additional Paid-in Capital [Member]
Other Comprehensive Income (Loss), Net of Tax				$ 5.0
Common Stock, Dividends, Per Share, Declared	$ 0.1000
Balance at Sep. 30, 2018		$ 1.6	$ (850.0)	(32.8)	$ 1.5	$ 1,444.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared						15.8
Stock repurchased under buyback program						0.0
Stock-based compensation						2.3
Shares retained for employee taxes						1.4
Stock issued under stock compensation plans	$ 0.0					3.6
Net Income (Loss) Attributable to Parent	(10.1)
Net Income (Loss) Attributable to Noncontrolling Interest					(0.4)
Balance at Mar. 31, 2019	548.8	1.6	(860.1)	(27.8)	1.9	1,433.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to Additional Paid in Capital, Other						0.0
Payments to Noncontrolling Interests	$ 0.0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					0.0
Other Comprehensive Income (Loss), Net of Tax				5.8
Common Stock, Dividends, Per Share, Declared	$ 0.0500
Balance at Dec. 31, 2018		1.6	(871.0)	(33.6)	1.7	1,440.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared						7.9
Stock repurchased under buyback program						0.0
Stock-based compensation						0.6
Shares retained for employee taxes						0.2
Stock issued under stock compensation plans	$ 0.0					0.5
Net Income (Loss) Attributable to Parent	10.9
Net Income (Loss) Attributable to Noncontrolling Interest					(0.2)
Balance at Mar. 31, 2019	548.8	1.6	(860.1)	(27.8)	1.9	1,433.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to Additional Paid in Capital, Other						0.0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					0.0
Common Stock, Value, Issued	1.6
Other Comprehensive Income (Loss), Net of Tax	$ 2.9			2.9
Common Stock, Dividends, Per Share, Declared	$ 0.1050
Balance at Sep. 30, 2019	$ 592.3	1.6	(786.2)	(36.0)	2.2	1,410.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared						16.6
Stock repurchased under buyback program						(5.0)
Stock-based compensation						2.7
Shares retained for employee taxes						0.7
Stock issued under stock compensation plans	0.0					2.2
Net Income (Loss) Attributable to Parent	34.1
Net Income (Loss) Attributable to Noncontrolling Interest					0.0
Balance at Mar. 31, 2020	606.5	1.6	(752.1)	(33.1)	0.0	1,390.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to Additional Paid in Capital, Other						(3.2)
Payments to Noncontrolling Interests	$ 5.2
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(2.2)
Other Comprehensive Income (Loss), Net of Tax				(1.1)
Common Stock, Dividends, Per Share, Declared	$ 0.0525
Balance at Dec. 31, 2019		1.6	(775.9)	(32.0)	0.0	1,401.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared						8.3
Stock repurchased under buyback program						(5.0)
Stock-based compensation						1.3
Shares retained for employee taxes						0.0
Stock issued under stock compensation plans	$ 0.0					0.8
Net Income (Loss) Attributable to Parent	23.8
Net Income (Loss) Attributable to Noncontrolling Interest					0.0
Balance at Mar. 31, 2020	606.5	$ 1.6	$ (752.1)	$ (33.1)	0.0	1,390.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to Additional Paid in Capital, Other						$ 0.0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					$ 0.0
Common Stock, Value, Issued	$ 1.6