CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2018	Sep. 30, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value (in usd per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	88,857,000	88,857,000
Common stock, shares outstanding	29,056,000	29,015,000
Treasury stock, shares	59,801,000	59,842,000