Earnings Per Share - Antidilutive Securities (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Stock options
Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	360	529	227	529
Time-based restricted stock
Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	284	645	52	645
Performance-based restricted stock
Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0	796	0	796