Equity (Narrative) (Details)	6 Months Ended
	Mar. 31, 2019 plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity incentive compensation plans maintained by the company	4
Employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, average minimum vesting period (in years)	4 years
Stock options, average maximum vesting period (in years)	5 years
Stock options, contractual life (in years)	10 years