GOODWILL AND RELATED INTANGIBLE ASSETS

Goodwill

The changes in the carrying amount of goodwill for the three months ended March 31, 2019 are as follows (in thousands):



	Residential Products		Industrial and Infrastructure Products		Renewable Energy & Conservation			Total
Balance at December 31, 2018	$	198,075	$	53,769	$	71,827		$	323,671
Adjustments to prior year acquisitions	—		—		(172		)	(172		)
Foreign currency translation	—		116		(42		)	74
Balance at March 31, 2019	$	198,075	$	53,885	$	71,613		$	323,573

Acquired Intangible Assets

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



	March 31, 2019				December 31, 2018
	Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization		Estimated Life
Indefinite-lived intangible assets:
Trademarks	$	43,870	$	—	$	43,870	$	—	Indefinite
Finite-lived intangible assets:
Trademarks	6,114		3,669		6,094		3,518		3 to 15 Years
Unpatented technology	28,644		14,352		28,644		13,881		5 to 20 Years
Customer relationships	70,348		36,791		70,419		35,678		5 to 17 Years
Non-compete agreements	1,649		1,293		1,649		1,224		4 to 10 Years
	106,755		56,105		106,806		54,301
Total acquired intangible assets	$	150,625	$	56,105	$	150,676	$	54,301

The following table summarizes the acquired intangible asset amortization expense for the three months ended March 31 (in thousands):



	Three Months Ended March 31,
	2019		2018
Amortization expense	$	1,797	$	2,139

Amortization expense related to acquired intangible assets for the remainder of fiscal 2019 and the next five years thereafter is estimated as follows (in thousands):



	2019		2020		2021		2022		2023		2024
Amortization expense	$	5,390	$	6,895	$	6,700	$	6,222	$	5,684	$	5,428