Goodwill and other intangible assets (Tables)

6 Months Ended

Jun. 30, 2015

Goodwill and Intangible Assets Disclosure [Abstract]

Changes in the carrying amount of goodwill

The changes in the carrying amount of goodwill were as follows:

Six Months Ended June 30, 2015	Balance as of January 1, 2015*		Goodwill Acquired During the Year		Balance as of June 30, 2015*
	(In thousands)
Natural gas distribution	$	345,736	$	—	$	345,736
Pipeline and energy services	9,737		—		9,737
Construction materials and contracting	176,290		—		176,290
Construction services	103,441		—		103,441
Total	$	635,204	$	—	$	635,204

* Balance is presented net of accumulated impairment of $12.3 million at the pipeline and energy services segment, which occurred in prior periods.

Six Months Ended June 30, 2014	Balance as of January 1, 2014*		Goodwill Acquired During the Year		Balance as of June 30, 2014*
	(In thousands)
Natural gas distribution	$	345,736	$	—	$	345,736
Pipeline and energy services	9,737		—		9,737
Construction materials and contracting	176,290		—		176,290
Construction services	104,276		—		104,276
Total	$	636,039	$	—	$	636,039

* Balance is presented net of accumulated impairment of $12.3 million at the pipeline and energy services segment, which occurred in prior periods.

Year Ended December 31, 2014	Balance as of January 1, 2014*		Goodwill Acquired During the Year/Other			Balance as of December 31, 2014*
	(In thousands)
Natural gas distribution	$	345,736	$	—		$	345,736
Pipeline and energy services	9,737		—			9,737
Construction materials and contracting	176,290		—			176,290
Construction services	104,276		(835		)	103,441
Total	$	636,039	$	(835	)	$	635,204

  * Balance is presented net of accumulated impairment of $12.3 million at the pipeline and energy services segment, which occurred in prior periods.

Other amortizable intangible assets

Other amortizable intangible assets were as follows:

	June 30, 2015			June 30, 2014			December 31, 2014
	(In thousands)
Customer relationships	$	20,975		$	21,310		$	21,310
Accumulated amortization	(16,065		)	(14,734		)	(15,556		)
	4,910			6,576			5,754
Noncompete agreements	4,409			5,080			5,080
Accumulated amortization	(3,581		)	(3,936		)	(4,098		)
	828			1,144			982
Other	8,300			10,921			10,921
Accumulated amortization	(5,532		)	(7,375		)	(7,817		)
	2,768			3,546			3,104
Total	$	8,506		$	11,266		$	9,840