Goodwill and Related Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Changes in Carrying Amount of Goodwill

The changes in the carrying amount of goodwill for the years ended December 31 were as follows (in thousands):



	Residential Products		Industrial and Infrastructure Products			Renewable Energy and Conservation			Total
Balance at December 31, 2016	$	181,285	$	53,884		$	68,863		$	304,032
Acquired goodwill	16,790		—			—			16,790
Adjustments to prior year acquisitions	—		—			(832		)	(832		)
Foreign currency translation	—		396			688			1,084
Balance at December 31, 2017	$	198,075	$	54,280		$	68,719		$	321,074
Acquired goodwill	—		—			3,051			3,051
Adjustments to prior year acquisitions	—		(38		)	—			(38		)
Foreign currency translation	—		(473		)	57			(416		)
Balance at December 31, 2018	$	198,075	$	53,769		$	71,827		$	323,671

Schedule of Acquired Intangible Assets

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



	December 31, 2018				December 31, 2017
	Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization		Estimated Useful Life
Indefinite-lived intangible assets:
Trademarks	$	43,870	$	—	$	45,107	$	—	Indefinite
Finite-lived intangible assets:
Trademarks	6,094		3,518		5,876		3,062		3 to 15 Years
Unpatented technology	28,644		13,881		28,107		12,033		5 to 20 Years
Customer relationships	70,419		35,678		80,707		39,652		5 to 17 Years
Non-compete agreements	1,649		1,224		1,649		931		4 to 10 Years
	106,806		54,301		116,339		55,678
Total acquired intangible assets	$	150,676	$	54,301	$	161,446	$	55,678

Schedule of Acquired Intangible Asset Amortization Expense

The following table summarizes the impairment charges for the years ended December 31 (in thousands):



	2018				2017				2016
	Indefinite-lived intangibles (1)		Definite-lived intangibles (2)		Indefinite-lived intangibles (3)		Definite-lived intangibles		Indefinite-lived intangibles (4)		Definite-lived intangibles (5)
Residential Products	$	200	$	—	$	—	$	—	$	—	$	—
Industrial and Infrastructure Products	—		—		—		—		7,980		—
Renewable Energy and Conservation	1,037		315		247		—		1,068		198
Impairment charges	$	1,237	$	315	$	247	$	—	$	9,048	$	198

(1) Residential Products impairment charges due to annual testing. Renewable Energy and Conservation impairment charges due to the annual testing in its international solar racking business and restructuring in its domestic greenhouse business.

(2) Renewable Energy and Conservation impairment charges due to the restructuring in its domestic greenhouse business.

(3) Renewable Energy and Conservation impairment charges due to the discontinuation of its domestic greenhouse business in China.

(4) Industrial and Infrastructure Products impairment charges due to discontinuation of U.S. bar grating product line and annual testing. Renewable Energy and Conservation impairment due to discontinuation of European residential solar racking business and annual testing.

(5) Renewable Energy and Conservation impairment due to discontinuation of European residential solar racking business.

Schedule of Intangible Assets Amortization Expense

The following table summarizes amortization expense for the years ended December 31 (in thousands):



	2018		2017		2016
Amortization expense	$	8,222	$	8,761	$	9,637

Schedule of Amortization Expense

Amortization expense related to acquired intangible assets for the next five years ended December 31 is estimated as follows (in thousands):



	2019		2020		2021		2022		2023
Amortization expense	$	7,213	$	6,921	$	6,726	$	6,248	$	5,709