Revenue from contracts with customers (Tables)

3 Months Ended

Mar. 31, 2018

Revenue from Contract with Customer [Abstract]

Disaggregation of revenue

For more information on the Company's business segments, see Note 13.

Three Months Ended March 31, 2018	Electric			Natural gas distribution			Pipeline and midstream			Construction materials and contracting			Construction services			Other			Total
	(in thousands)
Residential utility sales	$	35,183		$	192,886		$	—		$	—		$	—		$	—		$	228,069
Commercial utility sales	34,701			116,891			—			—			—			—			151,592
Industrial utility sales	8,770			7,809			—			—			—			—			16,579
Other utility sales	1,836			—			—			—			—			—			1,836
Natural gas transportation	—			11,179			21,818			—			—			—			32,997
Natural gas gathering	—			—			2,270			—			—			—			2,270
Natural gas storage	—			—			3,134			—			—			—			3,134
Contracting services	—			—			—			74,064			—			—			74,064
Construction materials	—			—			—			173,591			—			—			173,591
Intrasegment eliminations*	—			—			—			(34,270		)	—			—			(34,270		)
Inside specialty contracting	—			—			—			—			233,821			—			233,821
Outside specialty contracting	—			—			—			—			87,181			—			87,181
Other	8,252			3,999			3,326			—			(86		)	2,696			18,187
Intersegment eliminations	—			—			(21,759		)	(101		)	(11		)	(2,638		)	(24,509		)
Revenues from contracts with customers	88,742			332,764			8,789			213,284			320,905			58			964,542
Revenues out of scope	(1,338		)	(100		)	44			—			13,145			—			11,751
Total external operating revenues	$	87,404		$	332,664		$	8,833		$	213,284		$	334,050		$	58		$	976,293

* Intrasegment revenues are presented within the construction materials and contracting segment to highlight the focus on vertical integration as this segment sells materials to both third parties and internal customers. Due to consolidation requirements, these revenues must be eliminated against construction materials to arrive at the external operating revenue total for the segment.

Contract balances

The change in contract assets and liabilities were as follows:

	March 31, 2018			December 31, 2017			Change			Location on Consolidated Balance Sheets
	(In thousands)
Contract assets	$	132,610		$	122,184		$	10,426		Receivables, net
Contract liabilities - current	(80,905		)	(71,479		)	(9,426		)	Accounts payable
Contract liabilities - noncurrent	(399		)	—			(399		)	Deferred credits and other liabilities - other
Net contract assets (liabilities)	$	51,306		$	50,705		$	601