Regulatory Assets and Liabilities

6 Months Ended

Mar. 31, 2021

Regulatory Assets and Liabilities Disclosure [Abstract]

Regulatory assets generally represent incurred costs that have been deferred because such costs are probable of future recovery in customer rates. Regulatory liabilities generally represent obligations to make refunds to customers for previous collections for costs that are not likely to be incurred or deferral of gains that will be credited to customers in future periods. Components of regulatory assets and regulatory liabilities are summarized in the table below.


Regulatory Assets and Liabilities
	At March 31, 2021		At September 30, 2020
Current regulatory assets

Unrealized losses on interest rate derivatives	$	114	$	114

Unrealized losses on commodity derivatives	—		4


Fuel cost adjustment receivable	41		12

Total current regulatory assets	155		130

Non-current regulatory assets
Deferred pension costs and other post-retirement benefits costs	5,009		5,193
Non-nuclear decommissioning costs	2,604		2,512

Unrealized losses on interest rate derivatives	986		1,506
Nuclear decommissioning costs	482		896

Unrealized losses on commodity derivatives	4		—


Other non-current regulatory assets	145		138
Total non-current regulatory assets	9,230		10,245
Total regulatory assets	$	9,385	$	10,375

Current regulatory liabilities
Fuel cost adjustment tax equivalents	$	115	$	115

Unrealized gains on commodity derivatives	26		26
Total current regulatory liabilities	141		141

Non-current regulatory liabilities

Unrealized gains on commodity derivatives	5		23


Total regulatory liabilities	$	146	$	164