Business segment data

3 Months Ended

Mar. 31, 2017

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 midstream segment provides natural gas transportation, underground storage and gathering services through regulated and nonregulated pipeline systems primarily in the Rocky Mountain and northern Great Plains regions of the United States. This segment also provides cathodic protection and other energy-related services. For information on the Company's natural gas and oil gathering and processing facility sold on January 1, 2017, see Note 8.

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 communication 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 other 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, pollution liability and other coverages. Centennial Capital also owns certain real and personal property. The Other category also includes certain general and administrative costs (reflected in operation and maintenance expense) and interest expense which were previously allocated to the refining business and Fidelity and do not meet the criteria for income (loss) from discontinued operations. The Other category also includes Centennial Resources' former investment in Brazil.

Discontinued operations includes the results and supporting activities of Dakota Prairie Refining and Fidelity other than certain general and administrative costs and interest expense as described above. Dakota Prairie Refining refined crude oil and produced and sold diesel fuel, naphtha, ATBs and other by-products of the production process. In the second quarter of 2016, the Company sold all of the outstanding membership interests in Dakota Prairie Refining. Fidelity engaged in oil and natural gas development and production activities in the Rocky Mountain and Mid-Continent/Gulf States regions of the United States. Between September 2015 and March 2016, the Company entered into purchase and sale agreements to sell all of Fidelity's oil and natural gas assets. The completion of these sales occurred between October 2015 and April 2016. For more information on discontinued operations, see Note 8.

The information below follows the same accounting policies as described in Note 1 of the Company's Notes to Consolidated Financial Statements in the 2016 Annual Report. Information on the Company's businesses was as follows:

	Three Months Ended
	March 31,
	2017			2016
	(In thousands)
External operating revenues:
Regulated operations:
Electric	$	88,225		$	82,923
Natural gas distribution	342,519			299,395
Pipeline and midstream	2,870			3,547
	433,614			385,865
Nonregulated operations:
Pipeline and midstream	3,643			8,697
Construction materials and contracting	200,776			209,852
Construction services	299,572			255,500
Other	320			300
	504,311			474,349
Total external operating revenues	$	937,925		$	860,214
Intersegment operating revenues:
Regulated operations:
Electric	$	—		$	—
Natural gas distribution	—			—
Pipeline and midstream	21,489			21,098
	21,489			21,098
Nonregulated operations:
Pipeline and midstream	34			84
Construction materials and contracting	86			118
Construction services	6			462
Other	1,743			1,669
	1,869			2,333
Intersegment eliminations	(23,358		)	(23,431		)
Total intersegment operating revenues	$	—		$	—

	Three Months Ended
	March 31,
	2017			2016
	(In thousands)
Earnings on common stock:
Regulated operations:
Electric	$	14,333		$	11,119
Natural gas distribution	27,861			25,241
Pipeline and midstream	4,557			5,288
	46,751			41,648
Nonregulated operations:
Pipeline and midstream	(628		)	1
Construction materials and contracting	(19,912		)	(14,471		)
Construction services	7,362			5,974
Other	(279		)	(1,458		)
	(13,457		)	(9,954		)
Intersegment eliminations*	2,173			—
Earnings on common stock before income (loss) from discontinued operations	35,467			31,694
Income (loss) from discontinued operations, net of tax*	1,687			(18,036		)
Loss from discontinued operations attributable to noncontrolling interest	—			(11,040		)
Total earnings on common stock	$	37,154		$	24,698

* Includes an elimination for the presentation of income tax adjustments between continuing and

discontinued operations.