Stockholders' Equity (Changes in Nonvested Stock Options) (Details) - $ / shares shares in Thousands	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Stock-Based Compensation
Number of Options, beginning balance	2,075
Weighted-Average Grant Date Fair Value Per Share, beginning balance	$ 14.90
Options granted, Number of options	791
Options granted, Weighted-Average Grant Date Fair Value Per Share	$ 24.98	$ 13.39	$ 17.02
Options vested, Number of options	(763)
Options vested, Weighted-Average Grant Date Fair Value Per Share	$ 15.26
Options forfeited, Number of options	(31)
Options forfeited, Weighted-Average Grant Date Fair Value Per Share	$ 15.40
Number of Options, ending balance	2,072	2,075
Weighted-Average Grant Date Fair Value Per Share, ending balance	$ 18.61	$ 14.90