Earnings Per Share - Diluted Shares Calculation (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Basic shares (in shares)	32,140	31,969	32,097	31,931
Shares issuable upon vesting of restricted stock (in shares)	466	0	0	0
Shares issuable upon exercise of options (in shares)	115	0	0	0
Diluted shares (in shares)	32,721	31,969	32,097	31,931