Stockholders' Equity (Changes in Nonvested Stock Options) (Details) shares in Thousands	3 Months Ended
	Dec. 31, 2017 $ / shares shares
Stock-Based Compensation
Number of Options, beginning balance | shares	2,072
Weighted-Average Grant Date Fair Value Per Share, beginning balance | $ / shares	$ 18.61
Options granted, Number of options | shares	744
Options granted, Weighted-Average Grant Date Fair Value Per Share | $ / shares	$ 25.68
Options vested, Number of options | shares	(787)
Options vested, Weighted-Average Grant Date Fair Value Per Share | $ / shares	$ 17.54
Options forfeited, Number of options | shares	(9)
Options forfeited, Weighted-Average Grant Date Fair Value Per Share | $ / shares	$ 19.82
Number of Options, ending balance | shares	2,020
Weighted-Average Grant Date Fair Value Per Share, ending balance | $ / shares	$ 21.63