Regulatory Assets and Liabilities

6 Months Ended

Mar. 31, 2016

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 deferrals 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, 2016		At September 30, 2015
Current regulatory assets
Deferred nuclear generating units	$	237	$	237
Unrealized losses on commodity derivatives	190		162
Environmental agreements	48		47
Environmental cleanup costs - Kingston ash spill	43		43
Fuel cost adjustment receivable	30		15
Other current regulatory assets	2		2
Total current regulatory assets	550		506

Non-current regulatory assets
Deferred pension costs and other post-retirement benefits costs	5,549		5,565
Unrealized losses on interest rate derivatives	1,409		1,236
Nuclear decommissioning costs	982		1,003
Deferred nuclear generating units	953		1,042
Non-nuclear decommissioning costs	818		828
Environmental cleanup costs - Kingston ash spill	320		348
Unrealized losses on commodity derivatives	103		63
Environmental agreements	32		55
Other non-current regulatory assets	266		278
Total non-current regulatory assets	10,432		10,418
Total regulatory assets	$	10,982	$	10,924

Current regulatory liabilities
Fuel cost adjustment tax equivalents	$	150	$	164
Unrealized gains on commodity derivatives	3		—
Total current regulatory liabilities	153		164

Non-current regulatory liabilities
Unrealized gains on commodity derivatives	1		2
Total non-current regulatory liabilities	1		2
Total regulatory liabilities	$	154	$	166