Our regulatory assets and liabilities result from our application of the provisions of Topic 980 and are reflected on our balance sheet. Current regulatory assets are included in Exchange gas offset and 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, 2016 and 2015:



	2016		2015
	(Thousands of Dollars)
Current regulatory assets:
Environmental costs	$	—	$	1,300
Levelized depreciation	3,864		2,731
Fuel recovery	—		178
Total current regulatory assets	3,864		4,209
Noncurrent regulatory assets:
Environmental costs	—		(1,068		)
Grossed-up deferred taxes on equity funds used during construction	13,051		13,809
Levelized depreciation	21,849		26,493
Asset retirement obligations, net	—		1,619
Total noncurrent regulatory assets	34,900		40,853
Total regulatory assets	$	38,764	$	45,062
Current regulatory liabilities:
Fuel recovery	$	1,466	$	—
Noncurrent regulatory liabilities:
Postretirement benefits	30,587		26,802
Asset retirement obligations, net	130		—
Total noncurrent regulatory liabilities	30,717		26,802
Total regulatory liabilities	$	32,183	$	26,802