Regulatory Assets and Liabilities

3 Months Ended

Dec. 31, 2015

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 December 31, 2015		At September 30, 2015
Current regulatory assets
Deferred nuclear generating units	$	237	$	237
Unrealized losses on commodity derivatives	169		162
Environmental agreements	49		47
Environmental cleanup costs - Kingston ash spill	43		43
Fuel cost adjustment receivable	3		15
Other current regulatory assets	2		2
Total current regulatory assets	503		506

Non-current regulatory assets
Deferred pension costs and other post-retirement benefits costs	5,556		5,565
Unrealized losses on interest rate derivatives	1,147		1,236
Nuclear decommissioning costs	970		1,003
Environmental cleanup costs - Kingston ash spill	331		348
Non-nuclear decommissioning costs	835		828
Deferred nuclear generating units	1,004		1,042
Environmental agreements	41		55
Unrealized losses on commodity derivatives	81		63
Other non-current regulatory assets	272		278
Total non-current regulatory assets	10,237		10,418
Total regulatory assets	$	10,740	$	10,924

Current regulatory liabilities
Fuel cost adjustment tax equivalents	$	157	$	164
Fuel cost adjustment payable	25		—
Total current regulatory liabilities	182		164

Non-current regulatory liabilities
Unrealized gains on commodity derivatives	4		2
Total non-current regulatory liabilities	4		2
Total regulatory liabilities	$	186	$	166