Goodwill

Goodwill represents the difference between the purchase price and the estimated fair value of identifiable assets acquired and liabilities assumed. Goodwill acquired in a business combination and determined to have an indefinite useful life is not amortized, but instead is tested for impairment at least annually in accordance with ASC 350.

The following table represents the change in the carrying value of goodwill for the nine months ended September 30, 2019 (amounts in thousands):


Balance as of December 31, 2018	$	326,735
Cumulative translation adjustment		(793	)
Acquisition of C Technologies, Inc.		142,903

Balance as of September 30, 2019	$	468,845

During each of the fourth quarters of 2018, 2017 and 2016, we completed our annual impairment assessments and concluded that goodwill was not impaired in any of those years. The Company has not identified any “triggering” events which indicate an impairment of goodwill in the three months ended September 30, 2019.

Other Intangible Assets

Intangible assets, except for the ATF tradename, are amortized over their useful lives using the estimated economic benefit method, as applicable, and the amortization expense is recorded within selling, general and administrative expense in the Company’s statements of comprehensive income (loss). The Company reviews its indefinite-lived intangible assets not subject to amortization, including the ATF tradename, to determine if adverse conditions exist or a change in circumstances exists that would indicate an impairment. Intangible assets and their related useful lives are reviewed at least annually to determine if any adverse conditions exist that would indicate the carrying value of these assets may not be recoverable. More frequent impairment assessments are conducted if certain conditions exist, including a change in the competitive landscape, any internal decisions to pursue new or different technology strategies, a loss of a significant customer, or a significant change in the marketplace, including changes in the prices paid for our products or changes in the size of the market for our products. An impairment results if the carrying value of the asset exceeds the estimated fair value of the asset. If the estimate of an intangible asset’s remaining useful life is changed, the remaining carrying amount of the intangible asset is amortized prospectively over the revised remaining useful life. The Company continues to believe that its intangible assets are recoverable at September 30, 2019.

Intangible assets, net consisted of the following at September 30, 2019:


	September 30, 2019
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Weighted Average Useful Life (in years)
	(Amounts in thousands)
Finite-lived intangible assets:
Technology — developed	$	82,088	$	(8,533	)	$	73,555		19
Patents		240		(240	)		—		8
Customer relationships		160,467		(22,769	)		137,698		15
Trademarks		3,751		(286	)		3,465		20
Other intangibles		1,696		(825	)		871		3

Total finite-lived intangible assets		248,242		(32,653	)		215,589		16
Indefinite-lived intangible asset:
Trademarks		700		—			700		—

Total intangible assets	$	248,942	$	(32,653	)	$	216,289

Intangible assets consisted of the following at December 31, 2018:


	December 31, 2018
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Weighted Average Useful Life (in years)
	(Amounts in thousands)
Finite-lived intangible assets:
Technology — developed	$	53,315	$	(5,942	)	$	47,373		19
Patents		240		(240	)		—		8
Customer relationships		101,460		(16,609	)		84,851		14
Trademarks		2,160		(159	)		2,001		20
Other intangibles		1,061		(548	)		513		3

Total finite-lived intangible assets		158,236		(23,498	)		134,738		16
Indefinite-lived intangible asset:
Trademarks		700		—			700		—

Total intangible assets	$	158,936	$	(23,498	)	$	135,438

The increase in intangible assets during 2019 is related to the acquisition of C Technologies on May 31, 2019. See Note 3,

“Acquisition of C Technologies, Inc.”

for more information.

Amortization expense for finite-lived intangible assets was $3.9 million and $2.6 million for the three months ended September 30, 2019 and 2018, respectively. Amortization expense for finite-lived intangible assets was $9.6 million and $7.9 million for the nine months ended September 30, 2019 and 2018, respectively. As of September 30, 2019, the Company expects to record the following amortization expense (amounts in thousands):


	Estimated
	Amortization
Nine Months Ended September 30,	Expense
2019 (remaining three months)	$	3,918
2020		15,129
2021		14,633
2022		14,631
2023		14,631
2024 and thereafter		152,647

Total	$	215,589