Income Taxes (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | |
---|---|---|---|
Jun. 30, 2020 |
Jun. 30, 2020 |
Sep. 30, 2019 |
|
Income Tax Contingency [Line Items] | |||
Reduction of deferred tax liability | $ 32,500 | ||
Regulatory liabilities | 1,405,246 | $ 1,405,246 | $ 1,386,126 |
Income tax benefit | 21,000 | 21,000 | |
Deferred Income Tax Charge - Remeasurement Due to Law Change under the Reg Liability | |||
Income Tax Contingency [Line Items] | |||
Regulatory liabilities | $ 12,100 | $ 12,100 |