Goodwill and other intangible assets (Tables)

9 Months Ended

Sep. 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:

Nine Months Ended September 30, 2015	Balance as of January 1, 2015		*	Goodwill Acquired During the Year		Balance as of September 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.

Nine Months Ended September 30, 2014	Balance as of January 1, 2014		*	Goodwill Acquired During the Year		Balance as of September 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:

	September 30, 2015			September 30, 2014			December 31, 2014
	(In thousands)
Customer relationships	$	20,975		$	21,310		$	21,310
Accumulated amortization	(16,455		)	(15,116		)	(15,556		)
	4,520			6,194			5,754
Noncompete agreements	4,409			5,080			5,080
Accumulated amortization	(3,632		)	(4,021		)	(4,098		)
	777			1,059			982
Other	8,300			10,921			10,921
Accumulated amortization	(5,689		)	(7,578		)	(7,817		)
	2,611			3,343			3,104
Total	$	7,908		$	10,596		$	9,840