CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Millions	Total	Common Stock	Preferred Stock	Paid-in Capital	Retained Earnings	AOCI	[1]
BALANCE at Sep. 30, 2018	$ 2,255.4	$ 50.7		$ 1,482.7	$ 715.6	$ 6.4
BALANCE (in shares) at Sep. 30, 2018		50,671,903
Stockholders' Equity Rollforward
Net Income	67.3				67.3
Dividend reinvestment plan	0.4			0.4
Dividend reinvestment plan (in shares)		5,063
Stock-based compensation costs	2.0			2.0
Stock issued under stock-based compensation plans		$ 0.1		(0.1)
Stock issued under stock-based compensation (in shares)		74,835
Employees’ tax withholding for stock-based compensation	(2.3)	$ (0.1)		(2.2)
Employee's tax withholding for stock-based compensation (in shares)		(27,633)
Dividends declared on common stock	(30.0)				(30.0)
Other comprehensive income/loss, net of tax	(8.2)					(8.2)
BALANCE at Dec. 31, 2018	2,284.6	$ 50.7		1,482.8	752.9	(1.8)
BALANCE (in shares) at Dec. 31, 2018		50,724,168
BALANCE at Sep. 30, 2019	2,543.0	$ 51.0	$ 242.0	1,505.8	775.5	(31.3)
BALANCE (in shares) at Sep. 30, 2019		50,973,515
Stockholders' Equity Rollforward
Net Income	67.0				67.0
Dividend reinvestment plan	2.3			2.3
Dividend reinvestment plan (in shares)		28,764
Stock-based compensation costs	1.6			1.6
Stock issued under stock-based compensation plans		$ 0.1		(0.1)
Stock issued under stock-based compensation (in shares)		99,126
Employees’ tax withholding for stock-based compensation	(2.9)			(2.9)
Employee's tax withholding for stock-based compensation (in shares)		(37,945)
Temporary equity adjustment to redemption value	(0.1)				(0.1)
Dividends declared on common stock	(31.9)				(31.9)
Dividends declared on preferred stock	(7.4)				(7.4)
Other comprehensive income/loss, net of tax	14.4					14.4
BALANCE at Dec. 31, 2019	$ 2,586.0	$ 51.1	$ 242.0	$ 1,506.7	$ 803.1	$ (16.9)
BALANCE (in shares) at Dec. 31, 2019		51,063,460

[1] Accumulated other comprehensive income (loss)