Inventories and natural gas in storage

3 Months Ended

Mar. 31, 2016

Natural gas in storage for the Company's regulated operations is generally carried at average cost, or cost using the last-in, first-out method. Crude oil and refined products at Dakota Prairie Refinery are carried at lower of cost or market value using the last-in, first-out method. All other inventories are stated at the lower of average cost or market value. The portion of the cost of natural gas in storage expected to be used within one year is included in inventories. Inventories consisted of:



	March 31, 2016		March 31, 2015		December 31, 2015
	(In thousands)
Aggregates held for resale	$	127,101	$	112,029	$	115,854
Asphalt oil	52,065		89,578		36,498
Natural gas in storage (current)	11,305		9,303		21,023
Materials and supplies	21,645		57,073		16,997
Merchandise for resale	17,441		15,688		15,318
Crude oil	3,034		7,076		4,678
Refined products	14,022		—		8,498
Other	30,199		37,325		34,861
Total	$	276,812	$	328,072	$	253,727

The remainder of natural gas in storage, which largely represents the cost of gas required to maintain pressure levels for normal operating purposes, is included in other assets and was $49.1 million, $49.3 million and $49.1 million at March 31, 2016 and 2015, and December 31, 2015, respectively.