Inventories and natural gas in storage

6 Months Ended

Jun. 30, 2015

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:



	June 30, 2015		June 30, 2014		December 31, 2014
	(In thousands)
Aggregates held for resale	$	123,457	$	112,129	$	108,161
Asphalt oil	79,422		76,525		42,135
Materials and supplies	22,594		58,089		54,282
Merchandise for resale	16,140		25,507		24,420
Refined products	16,065		—		—
Natural gas in storage (current)	11,310		10,903		19,302
Crude oil	8,101		—		5,045
Other	37,316		35,420		36,065
Total	$	314,405	$	318,573	$	289,410

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 $49.3 million, $47.4 million and $49.3 million at June 30, 2015 and 2014, and December 31, 2014, respectively.