Our regulatory assets and liabilities result from our application of the provisions of ASC Topic 980 and are reflected on our Balance Sheet. Current regulatory assets are included in Prepayments and other. Current regulatory liabilities are included in Exchange gas offset. These balances are presented on our Balance Sheet on a gross basis and are recoverable or refundable over various periods. Below are the details of our regulatory assets and liabilities as of December 31, 2018 and 2017:



	2018		2017
	(Thousands of Dollars)
Current regulatory assets:
Levelized depreciation	$	414	$	4,707
Fuel Recovery	6,619		—
Total current regulatory assets	7,033		4,707
Noncurrent regulatory assets:
Grossed-up deferred taxes on equity funds used during construction	5,883		6,598
Levelized depreciation	18,109		16,149
Total noncurrent regulatory assets	23,992		22,747
Total regulatory assets	$	31,025	$	27,454

Current regulatory liabilities:
Fuel recovery	$	—	$	1,539
Noncurrent regulatory liabilities:
Postretirement benefits	36,154		34,089
Deferred federal taxes-liability	206,527		206,547
Deferred state taxes - liability	12,120		—
Customer tax refund	24,094		—
Asset retirement obligations, net	11,535		5,868
Total noncurrent regulatory liabilities	290,430		246,504
Total regulatory liabilities	$	290,430	$	248,043