Stockholders' Equity (Changes in Nonvested Stock Options) (Details) - $ / shares shares in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2017	Mar. 31, 2017
Stock-Based Compensation
Number of Options, beginning balance	1,304	2,075
Weighted-Average Grant Date Fair Value Per Share, beginning balance	$ 14.70	$ 14.90
Options granted, Number of options	780	780
Options granted, Weighted-Average Grant Date Fair Value Per Share	$ 25.05	$ 25.05
Options vested, Number of options	(3)	(761)
Options vested, Weighted-Average Grant Date Fair Value Per Share	$ 18.27	$ 15.25
Options forfeited, Number of options	(5)	(18)
Options forfeited, Weighted-Average Grant Date Fair Value Per Share	$ 14.77	$ 14.56
Number of Options, ending balance	2,076	2,076
Weighted-Average Grant Date Fair Value Per Share, ending balance	$ 18.58	$ 18.58