Consolidated Statements of Total Equity (Unaudited) Statement - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]
Beginning balances (shares) at Sep. 30, 2017		44,803,603
Retirement of treasury shares (shares)		(2,864,667)
Ending balances (shares) at Dec. 31, 2017		41,938,936
Beginning balances at Sep. 30, 2017	$ 631.3	$ 44.8	$ 549.4	$ 80.4	$ (44.5)	$ 1.2
Net income	(15.6)	0.0	0.0	(17.6)	0.0	2.0
Settlement of equity awards	(12.8)	0.0	(12.8)	0.0	0.0	0.0
Retirement of treasury shares	0.0	2.9	35.1	6.5	44.5	0.0
Stock-based compensation expense	4.5	0.0	4.5	0.0	0.0	0.0
Distributions to noncontrolling interests	(1.8)	0.0	0.0	0.0	0.0	(1.8)
Ending balances at Dec. 31, 2017	605.6	$ 41.9	506.0	56.3	0.0	1.4
Beginning balances (shares) at Sep. 30, 2017		44,803,603
Ending balances (shares) at Jun. 30, 2018		41,938,936
Beginning balances at Sep. 30, 2017	631.3	$ 44.8	549.4	80.4	(44.5)	1.2
Net income	(0.7)
Ending balances at Jun. 30, 2018	620.2	$ 41.9	506.2	70.2	0.0	1.9
Beginning balances (shares) at Dec. 31, 2017		41,938,936
Ending balances (shares) at Mar. 31, 2018		41,938,936
Beginning balances at Dec. 31, 2017	605.6	$ 41.9	506.0	56.3	0.0	1.4
Net income	4.6	0.0	0.0	4.5	0.0	0.1
Stock-based compensation expense	0.1	0.0	0.1	0.0	0.0	0.0
Distributions to noncontrolling interests	(0.3)	0.0	0.0	0.0	0.0	(0.3)
Ending balances at Mar. 31, 2018	610.0	$ 41.9	506.1	60.8	0.0	1.2
Ending balances (shares) at Jun. 30, 2018		41,938,936
Net income	10.3	$ 0.0	0.0	9.4	0.0	0.9
Stock-based compensation expense	0.1	0.0	0.1	0.0	0.0	0.0
Distributions to noncontrolling interests	(0.2)	0.0	0.0	0.0	0.0	(0.2)
Ending balances at Jun. 30, 2018	620.2	$ 41.9	506.2	70.2	0.0	1.9
Beginning balances (shares) at Sep. 30, 2018		41,939,403
Stock issued under employee incentive plans (shares)		20,463
Ending balances (shares) at Dec. 31, 2018		41,959,866
Beginning balances at Sep. 30, 2018	674.5	$ 41.9	506.3	125.1	0.0	1.2
Net income	3.9	0.0	0.0	3.3	0.0	0.6
Stock issued under employee incentive plans	0.0	0.1	(0.1)	0.0	0.0	0.0
Stock-based compensation expense	0.1	0.0	0.1	0.0	0.0	0.0
Distributions to noncontrolling interests	(0.5)	0.0	0.0	0.0	0.0	(0.5)
Ending balances at Dec. 31, 2018	678.0	$ 42.0	506.3	128.4	0.0	1.3
Beginning balances (shares) at Sep. 30, 2018		41,939,403
Ending balances (shares) at Jun. 30, 2019		41,959,866
Beginning balances at Sep. 30, 2018	674.5	$ 41.9	506.3	125.1	0.0	1.2
Net income	23.6
Ending balances at Jun. 30, 2019	695.3	$ 42.0	507.3	145.4	0.0	0.6
Beginning balances (shares) at Dec. 31, 2018		41,959,866
Ending balances (shares) at Mar. 31, 2019		41,959,866
Beginning balances at Dec. 31, 2018	678.0	$ 42.0	506.3	128.4	0.0	1.3
Net income	12.8	0.0	0.0	10.1	0.0	2.7
Stock-based compensation expense	0.1	0.0	0.1	0.0	0.0	0.0
Distributions to noncontrolling interests	(3.1)	0.0	0.0	0.0	0.0	(3.1)
Ending balances at Mar. 31, 2019	687.8	$ 42.0	506.4	138.5	0.0	0.9
Ending balances (shares) at Jun. 30, 2019		41,959,866
Net income	6.9	$ 0.0	0.0	6.9	0.0	0.0
Stock-based compensation expense	0.9	0.0	0.9	0.0	0.0	0.0
Distributions to noncontrolling interests	(0.3)	0.0	0.0	0.0	0.0	(0.3)
Ending balances at Jun. 30, 2019	$ 695.3	$ 42.0	$ 507.3	$ 145.4	$ 0.0	$ 0.6