GOODWILL AND RELATED INTANGIBLE ASSETS

Goodwill

The changes in the carrying amount of goodwill for the six months ended June 30, 2018 are as follows (in thousands):



	Residential Products		Industrial and Infrastructure Products			Renewable Energy & Conservation		Total
Balance at December 31, 2017	$	198,075	$	54,280		$	68,719	$	321,074
Foreign currency translation	—		(269		)	70		(199		)
Balance at June 30, 2018	$	198,075	$	54,011		$	68,789	$	320,875

Acquired Intangible Assets

Acquired intangible assets consist of the following (in thousands):



	June 30, 2018				December 31, 2017
	Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization		Estimated Life
Indefinite-lived intangible assets:
Trademarks	$	45,117	$	—	$	45,107	$	—	Indefinite
Finite-lived intangible assets:
Trademarks	5,830		3,273		5,876		3,062		5 to 15 Years
Unpatented technology	28,107		12,948		28,107		12,033		5 to 20 Years
Customer relationships	80,725		42,571		80,707		39,652		5 to 17 Years
Non-compete agreements	1,649		1,082		1,649		931		4 to 10 Years
	116,311		59,874		116,339		55,678
Total acquired intangible assets	$	161,428	$	59,874	$	161,446	$	55,678

The following table summarizes the acquired intangible asset amortization expense for the three and six months ended June 30 (in thousands):



	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017		2018		2017
Amortization expense	$	2,148	$	2,230	$	4,287	$	4,392

Amortization expense related to acquired intangible assets for the remainder of fiscal 2018 and the next five years thereafter is estimated as follows (in thousands):



	2018		2019		2020		2021		2022		2023
Amortization expense	$	4,048	$	7,653	$	7,141	$	6,538	$	6,126	$	5,587