Fair Value Measurements (Schedule of Qualitative Information) (Details) - item	6 Months Ended	12 Months Ended
	Mar. 31, 2020	Sep. 30, 2019
Minimum [Member] | Estimated Change Of Control Dates [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Estimated change of control date	Dec. 01, 2020	Sep. 01, 2020
Minimum [Member] | Discount Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant unobservable input	16.7	14.4
Minimum [Member] | Probability Of Change Of Control [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant unobservable input	10	10
Maximum [Member] | Estimated Change Of Control Dates [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Estimated change of control date	Dec. 01, 2021	Dec. 01, 2021
Maximum [Member] | Discount Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant unobservable input	21.0	16.8
Maximum [Member] | Probability Of Change Of Control [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant unobservable input	90	90