Defined Contribution Plan	12 Months Ended
Sep. 30, 2017
Compensation And Retirement Disclosure [Abstract]
Defined Contribution Plan	9. Defined Contribution Plan The Company has a 401(k) retirement and savings plan for the benefit of qualifying U.S. employees, and a defined contribution PRSA plan for the benefit of qualifying Ireland employees. For U.S. employees, the Company matches 50% of employee contributions on the first 6% of eligible compensation. For Ireland employees, the Company makes contributions of up to 8% of eligible compensation on employee contributions of up to 6% of eligible compensation. Company contributions totaling $0.7 million, $0.3 million and $0.3 million have been expensed in the years ended September 30, 2017, 2016 and 2015, respectively.

Defined Contribution Plan

12 Months Ended

Sep. 30, 2017

Compensation And Retirement Disclosure [Abstract]

9. Defined Contribution Plan

The Company has a 401(k) retirement and savings plan for the benefit of qualifying U.S. employees, and a defined contribution PRSA plan for the benefit of qualifying Ireland employees. For U.S. employees, the Company matches 50% of employee contributions on the first 6% of eligible compensation. For Ireland employees, the Company makes contributions of up to 8% of eligible compensation on employee contributions of up to 6% of eligible compensation. Company contributions totaling $0.7 million, $0.3 million and $0.3 million have been expensed in the years ended September 30, 2017, 2016 and 2015, respectively.