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				$ (0.8)
Common Stock, Dividends, Per Share, Declared	$ 0.0500
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						7.9
Stock-based compensation						1.7
Shares retained for employee taxes						1.2
Stock issued under stock compensation plans	$ 0.0					3.1
Net Income (Loss) Attributable to Parent	(21.0)
Net Income (Loss) Attributable to Noncontrolling Interest					(0.2)
Balance at Dec. 31, 2018	538.9	1.6	(871.0)	(33.6)	1.7	1,440.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Payments to Acquire Interest in Joint Venture	0.0
Adjustments to Additional Paid in Capital, Other						0.0
Payments to Noncontrolling Interests	0.0
Acquisition of remaining JV interest	0.0
Common Stock, Value, Issued	1.6
Other Comprehensive Income (Loss), Net of Tax	$ 4.0			4.0
Common Stock, Dividends, Per Share, Declared	$ 0.0525
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						8.3
Stock-based compensation						1.3
Shares retained for employee taxes						0.7
Stock issued under stock compensation plans	0.0					1.4
Net Income (Loss) Attributable to Parent	10.3
Net Income (Loss) Attributable to Noncontrolling Interest					0.0
Balance at Dec. 31, 2019	595.0	$ 1.6	$ (775.9)	$ (32.0)	$ 0.0	1,401.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Payments to Acquire Interest in Joint Venture	(2.2)
Adjustments to Additional Paid in Capital, Other						$ (3.2)
Payments to Noncontrolling Interests	5.2
Acquisition of remaining JV interest	(2.2)
Common Stock, Value, Issued	$ 1.6