Goodwill and other intangible assets (Tables)

12 Months Ended

Dec. 31, 2017

The changes in the carrying amount of goodwill for the year ended December 31, 2017, were as follows:



	Balance at January 1, 2017		Goodwill Acquired During the Year		Balance at December 31, 2017
	(In thousands)
Natural gas distribution	$	345,736	$	—	$	345,736
Construction materials and contracting	176,290		—		176,290
Construction services	109,765		—		109,765
Total	$	631,791	$	—	$	631,791

The changes in the carrying amount of goodwill for the year ended December 31, 2016, were as follows:



	Balance at January 1, 2016		*	Goodwill Acquired During the Year		Less Held for Sale		Balance at December 31, 2016
	(In thousands)
Natural gas distribution	$	345,736		$	—	$	—	$	345,736
Pipeline and midstream	9,737			—		9,737		—
Construction materials and contracting	176,290			—		—		176,290
Construction services	103,441			6,324		—		109,765
Total	$	635,204		$	6,324	$	9,737	$	631,791


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

Other amortizable intangible assets at December 31 were as follows:



	2017		2016
	(In thousands)
Customer relationships	$	15,248	$	17,145
Less accumulated amortization	13,382		13,917
	1,866		3,228
Noncompete agreements	2,430		2,430
Less accumulated amortization	1,805		1,658
	625		772
Other	6,990		7,768
Less accumulated amortization	5,644		5,843
	1,346		1,925
Total	$	3,837	$	5,925