Goodwill and other intangible assets

9 Months Ended

Sep. 30, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and other intangible assets

Goodwill and other intangible assets

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

	Balance at January 1, 2020		Goodwill Acquired During the Year		Measurement Period Adjustments		Balance at September 30, 2020
	(In thousands)
Natural gas distribution	$	345,736	$	—	$	—	$	345,736
Construction materials and contracting	217,234		6,483		—		223,717
Construction services	118,388		24,436		400		143,224
Total	$	681,358	$	30,919	$	400	$	712,677

	Balance at January 1, 2019		Goodwill Acquired During the Year		Measurement Period Adjustments		Balance at September 30, 2019
	(In thousands)
Natural gas distribution	$	345,736	$	—	$	—	$	345,736
Construction materials and contracting	209,421		14,473		(6,669)		217,225
Construction services	109,765		8,623		—		118,388
Total	$	664,922	$	23,096	$	(6,669)	$	681,349

	Balance at January 1, 2019		Goodwill Acquired During the Year		Measurement Period Adjustments		Balance at December 31, 2019
	(In thousands)
Natural gas distribution	$	345,736	$	—	$	—	$	345,736
Construction materials and contracting	209,421		14,482		(6,669)		217,234
Construction services	109,765		8,623		—		118,388
Total	$	664,922	$	23,105	$	(6,669)	$	681,358

Other amortizable intangible assets were as follows:

	September 30, 2020		September 30, 2019		December 31, 2019
	(In thousands)
Customer relationships	$	27,551	$	18,011	$	17,958
Less accumulated amortization	5,958		5,823		6,268
	21,593		12,188		11,690
Noncompete agreements	3,941		3,419		3,439
Less accumulated amortization	2,176		1,868		1,957
	1,765		1,551		1,482
Other	12,853		7,488		8,094
Less accumulated amortization	9,835		5,716		6,020
	3,018		1,772		2,074
Total	$	26,376	$	15,511	$	15,246

The previous tables include goodwill and intangible assets associated with the business combinations completed during 2020 and 2019. For more information related to these business combinations, see Note 9.

Amortization expense for amortizable intangible assets for the three and nine months ended September 30, 2020, was $2.1 million and $6.8 million, respectively. Amortization expense for amortizable intangible assets for the three and nine months ended September 30, 2019, was $500,000 and $1.6 million, respectively. Estimated amortization expense for identifiable intangible assets as of September 30, 2020, was:

	Remainder of 2020		2021		2022		2023		2024		Thereafter
	(In thousands)
Amortization expense	$	2,462	$	4,579	$	4,108	$	3,975	$	3,653	$	7,599