Goodwill and Other Intangible Assets

6 Months Ended

Jun. 30, 2018

Goodwill And Intangible Assets Disclosure [Abstract]

4.	Goodwill and Other Intangibles


	Mid-America		Southeast			West
	Group		Group			Group		Total
	(Dollars in Thousands)
Balance at January 1, 2018	$	281,403	$	50,346		$	1,828,541	$	2,160,290
Acquisitions		148,326		93,816			—		242,142
Divestitures		—		(927	)		—		(927	)
Balance at June 30, 2018	$	429,729	$	143,235		$	1,828,541	$	2,401,505

4.	Goodwill and Other Intangibles (continued)

Intangible assets subject to amortization consist of the following:

	Gross Amount		Accumulated Amortization			Net Balance
(Dollars in Thousands)	June 30, 2018
Noncompetition agreements	$	6,274	$	(6,162	)	$	112
Customer relationships		65,348		(19,480	)		45,868
Operating permits		458,952		(29,790	)		429,162
Use rights and other		16,496		(10,763	)		5,733
Trade names		12,800		(9,076	)		3,724
Total	$	559,870	$	(75,271	)	$	484,599

Intangible assets deemed to have an indefinite life and not being amortized consist of the following:

	Building Materials Business		Magnesia Specialties		Total
(Dollars in Thousands)	June 30, 2018
Operating permits	$	6,600	$	—	$	6,600
Use rights		20,642		—		20,642
Trade names		280		2,565		2,845
Total	$	27,522	$	2,565	$	30,087

Intangibles acquired during the year are as follows:

(Dollars in Thousands)	Amount		Weighted-average amortization period
Subject to amortization:
Customer relationships	$	20,620	12 years

Not subject to amortization:
Water rights		1,100	N/A
Total	$	21,720

4.	Goodwill and Other Intangibles (continued)

Total amortization expense for intangible assets for the six-months ended June 30, 2018 and 2017 was $7,108,000 and $7,167,000, respectively.

The estimated amortization expense for intangible assets for the second half of 2018 and for each of the next four years and thereafter is as follows:

(Dollars in Thousands)
July - December 2018	$	6,961
2019		13,724
2020		13,689
2021		12,998
2022		11,490
Thereafter		425,737
Total	$	484,599