Business segment data

3 Months Ended

Mar. 31, 2015

Segment Reporting [Abstract]

Business segment data

Business segment data

The Company's reportable segments are those that are based on the Company's method of internal reporting, which generally segregates the strategic business units due to differences in products, services and regulation. The internal reporting of these operating segments is defined based on the reporting and review process used by the Company's chief executive officer. The vast majority of the Company's operations are located within the United States.

The electric segment generates, transmits and distributes electricity in Montana, North Dakota, South Dakota and Wyoming. The natural gas distribution segment distributes natural gas in those states as well as in Idaho, Minnesota, Oregon and Washington. These operations also supply related value-added services.

The pipeline and energy services segment provides natural gas transportation, underground storage, processing and gathering services, as well as oil gathering, through regulated and nonregulated pipeline systems and processing facilities primarily in the Rocky Mountain and northern Great Plains regions of the United States. This segment recently commenced operations of Dakota Prairie Refinery in conjunction with Calumet to refine crude oil. The facility has begun producing diesel fuel and is expected to begin sales of diesel during May 2015. This segment also provides cathodic protection and other energy-related services.

The exploration and production segment is engaged in oil and natural gas development and production activities in the Rocky Mountain and Mid-Continent/Gulf States regions of the United States. The Company intends to market its exploration and production business in the future. The plan to market this business has been delayed due to low oil prices.

The construction materials and contracting segment mines aggregates and markets crushed stone, sand, gravel and related construction materials, including ready-mixed concrete, cement, asphalt, liquid asphalt and other value-added products. It also performs integrated contracting services. This segment operates in the central, southern and western United States and Alaska and Hawaii.

The construction services segment provides utility construction services specializing in constructing and maintaining electric and communications lines, gas pipelines, fire suppression systems, and external lighting and traffic signalization. This segment also provides utility excavation and inside electrical and mechanical services, and manufactures and distributes transmission line construction equipment and supplies.

The Other category includes the activities of Centennial Capital, which insures various types of risks as a captive insurer for certain of the Company's subsidiaries. The function of the captive insurer is to fund the deductible layers of the insured companies' general liability, automobile liability and pollution liability coverages. Centennial Capital also owns certain real and personal property. The Other category also included Centennial Resources' investment in the Brazilian Transmission Lines.

The information below follows the same accounting policies as described in Note 1 of the Company's Notes to Consolidated Financial Statements in the 2014 Annual Report. Information on the Company's businesses was as follows:

Three Months Ended March 31, 2015	External Operating Revenues		Inter- segment Operating Revenues			Earnings (Loss) on Common Stock
	(In thousands)
Electric	$	71,776	$	—		$	8,328
Natural gas distribution	330,573		—			21,450
Pipeline and energy services	25,095		21,341			4,018
	427,444		21,341			33,796
Exploration and production	49,710		5,226			(328,904		)
Construction materials and contracting	205,658		948			(14,635		)
Construction services	235,403		11,695			4,760
Other	295		1,772			(255		)
	491,066		19,641			(339,034		)
Intersegment eliminations	—		(40,982		)	(850		)
Total	$	918,510	$	—		$	(306,088	)

Three Months Ended March 31, 2014	External Operating Revenues		Inter- segment Operating Revenues			Earnings (Loss) on Common Stock
	(In thousands)
Electric	$	73,647	$	—		$	11,033
Natural gas distribution	374,233		—			27,263
Pipeline and energy services	43,661		18,276			4,349
	491,541		18,276			42,645
Exploration and production	116,669		20,867			20,939
Construction materials and contracting	164,423		4,017			(23,574		)
Construction services	269,892		3,738			16,568
Other	328		1,724			264
	551,312		30,346			14,197
Intersegment eliminations	—		(48,622		)	(351		)
Total	$	1,042,853	$	—		$	56,491

Earnings from electric, natural gas distribution and pipeline and energy services are substantially all from regulated operations. Earnings from exploration and production, construction materials and contracting, construction services and other are all from nonregulated operations.