Equity Incentive Plans - Performance-Based Grants (Details) - shares	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Restricted Stock, Performance Based Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance-based awards granted, percentage, minimum (as a percent)		0.00%	0.00%
Performance-based awards granted, percentage (as a percent)	100.00%	100.00%	100.00%
Performance-based awards granted, percentage, maximum threshold met (as a percent)	200.00%	200.00%	200.00%
Performance goal measurement period (in years)	3 years
Restricted Stock, Performance Based Shares, Fiscal Year 2015, Performance Goals Measured at End of Fiscal Year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance-based awards granted during fiscal year, performance goal measurement, percentage of units granted (as a percent)			60.00%
Forfeited (in shares)			495,684
Restricted Stock, Performance Based Shares, Fiscal Year 2015, Performance Goals Measured over Three Years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance-based awards granted during fiscal year, performance goal measurement, percentage of units granted (as a percent)			40.00%
Performance goal measurement period (in years)			3 years
Number of shares over the target grant (in shares)			351,066