Earnings Per Share - Diluted Shares Calculation (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Basic shares (in shares)	32,147	31,971	32,113	31,944
Diluted shares (in shares)	32,726	32,375	32,113	31,944
Restricted Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Shares issuable upon vesting of restricted stock (in shares)	500	352	0	0
Performance Shares
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Shares issuable upon vesting of restricted stock (in shares)	0	14	0	0
Stock Options
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Shares issuable upon vesting of restricted stock (in shares)	79	38	0	0