CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Noncontrolling Interest
Common Stock, Shares, Outstanding		41,938,936
Beginning Balances at Dec. 31, 2017	$ 605.6	$ 41.9	$ 506.0	$ 56.3	$ 1.4
Net income	70.0	0.0	0.0	68.8	1.2
Issuances of common stock, Value	0.0	0.0	0.0	0.0	0.0
Stock-based compensation expense	0.3	0.0	0.3	0.0	0.0
Distributions to noncontrolling interests	(1.4)	0.0	0.0	0.0	(1.4)
Issuance of common stock	0.0
Ending Balances at Sep. 30, 2018	674.5	$ 41.9	506.3	125.1	1.2
Issuances of common stock under employee benefit plans, Shares		(467)
Common Stock, Shares, Outstanding		41,939,403
Net income	36.3	$ 0.0	0.0	33.0	3.3
Issuances of common stock, Value	0.0	(0.1)	(0.1)	0.0	0.0
Stock-based compensation expense	1.3	0.0	1.3	0.0	0.0
Distributions to noncontrolling interests	(3.9)	0.0	0.0	0.0	(3.9)
Issuance of common stock	100.7	6.0	94.7	0.0	0.0
Ending Balances at Sep. 30, 2019	808.9	$ 48.0	602.2	158.1	0.6
Issuances of common stock under employee benefit plans, Shares		(20,463)
Shares Issued During Period, New Issues		6,037,500
Common Stock, Shares, Outstanding		47,997,366
Net income	61.7	$ 0.0	0.0	60.8	0.9
Issuances of common stock, Value	(0.1)	(0.1)	0.0	0.0	0.0
Shares withheld for payroll taxes, Value	(0.3)	0.0	(0.3)	0.0	0.0
Stock-based compensation expense	2.0	0.0	2.0	0.0	0.0
Distributions to noncontrolling interests	(0.6)	0.0	0.0	0.0	(0.6)
Issuance of common stock	0.0
Ending Balances at Sep. 30, 2020	$ 871.8	$ 48.1	$ 603.9	$ 218.9	$ 0.9
Issuances of common stock under employee benefit plans, Shares		(64,555)
Common Stock, Shares, Outstanding		48,061,921