Goodwill and other intangible assets (Tables)

12 Months Ended

Dec. 31, 2013

Goodwill [Line Items]

Changes in the carrying amount of goodwill

The changes in the carrying amount of goodwill for the year ended December 31, 2013, were as follows:

	Balance at January 1, 2013		*	Goodwill Acquired During the Year		Balance at December 31, 2013		*
	(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.

The changes in the carrying amount of goodwill for the year ended December 31, 2012, were as follows:

	Balance at January 1, 2012		*	Goodwill Acquired During the Year		**	Balance at December 31, 2012		*
	(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	103,168			1,108			104,276
Total	$	634,931		$	1,108		$	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.

** Includes contingent consideration that was not material related to an acquisition in a prior period.

Other amortizable intangible assets

Other amortizable intangible assets at December 31 were as follows:

	2013			2012
	(In thousands)
Customer relationships	$	21,310		$	21,310
Accumulated amortization	(13,726		)	(11,701		)
	7,584			9,609
Noncompete agreements	6,186			7,236
Accumulated amortization	(4,840		)	(5,326		)
	1,346			1,910
Other	10,995			10,979
Accumulated amortization	(6,826		)	(5,369		)
	4,169			5,610
Total	$	13,099		$	17,129