Earnings (Loss) Per Share Antidilutive shares excluded from earnings per share (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Stock Options
Antidilutive Securities Excluded from Computation of Earnings (Loss) Per Share
Antidilutive Securities Excluded from Computation of Earnings (Loss) Per Share, Amount	0.6	4.2	0.6	0.3
Stock Appreciation Rights
Antidilutive Securities Excluded from Computation of Earnings (Loss) Per Share
Antidilutive Securities Excluded from Computation of Earnings (Loss) Per Share, Amount	0.0	0.1	0.0	0.0
Restricted Stock Awards
Antidilutive Securities Excluded from Computation of Earnings (Loss) Per Share
Antidilutive Securities Excluded from Computation of Earnings (Loss) Per Share, Amount	0.0	0.7	0.0	0.0
Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings (Loss) Per Share
Antidilutive Securities Excluded from Computation of Earnings (Loss) Per Share, Amount	0.0	9.1	0.0	0.0