Goodwill and other intangible assets (Tables)

6 Months Ended

Jun. 30, 2013

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, 2013	Balance as of January 1, 2013*		Goodwill Acquired During the Year		Balance as of June 30, 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.

Six Months Ended June 30, 2012	Balance as of January 1, 2012*		Goodwill Acquired During the Year**		Balance as of June 30, 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		458		103,626
Total	$	634,931	$	458	$	635,389

* 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.

Year Ended December 31, 2012	Balance as of January 1, 2012*		Goodwill Acquired During the Year**		Balance as of 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 were as follows:

	June 30, 2013			June 30, 2012			December 31, 2012
	(In thousands)
Customer relationships	$	21,310		$	21,010		$	21,310
Accumulated amortization	(12,715		)	(10,690		)	(11,701		)
	8,595			10,320			9,609
Noncompete agreements	6,186			7,086			7,236
Accumulated amortization	(4,557		)	(5,057		)	(5,326		)
	1,629			2,029			1,910
Other	10,979			10,978			10,979
Accumulated amortization	(5,891		)	(4,671		)	(5,369		)
	5,088			6,307			5,610
Total	$	15,312		$	18,656		$	17,129