Earnings Per Share - Antidilutive Securities (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Stock options
Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	406	204	529	532
Time-based restricted stock
Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	94	170	643	850
Performance-based restricted stock
Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0	0	796	646