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, 2013 and 2012:



	2013		2012
	(Thousands of Dollars)
Current regulatory assets:
Environmental costs	$	1,300	$	1,300
Fuel recovery	—		1,249
Total current regulatory assets	1,300		2,549
Noncurrent regulatory assets:
Environmental costs	2,843		739
Grossed-up deferred taxes on equity funds used during construction	15,325		16,083
Levelized depreciation	33,261		33,979
Asset retirement obligations, net	6,712		9,497
Total noncurrent regulatory assets	58,141		60,298
Total regulatory assets	$	59,441	$	62,847
Current regulatory liabilities:
Fuel recovery	$	638	$	—
Noncurrent regulatory liabilities:
Postretirement benefits	19,047		17,395
Other	205		—
Total noncurrent regulatory liabilities	19,252		17,395
Total regulatory liabilities	$	19,890	$	17,395