Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment to decrease accumulated deficit	$ (562,972)	$ (571,207)
Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment to decrease accumulated deficit	$ 200