A summary of changes in the carrying amount of goodwill, by operating segment, for the six months ended June 30, 2020 is as follows:

	Automotive		Industrial		Total
Balance as of December 31, 2019	$	36,938	$	27,634	$	64,572
Exchange rate impact		42		15		57
Balance as of June 30, 2020	$	36,980	$	27,649	$	64,629

Other intangible assets and accumulated amortization balances as of June 30, 2020 and December 31, 2019 were as follows:

	Gross Carrying Value		Accumulated Amortization			Net Carrying Value
Definite-lived:
Customer relationships	$	89,352	$	(54,045	)	$	35,307
Technology		28,286		(20,919	)		7,367
Product development costs		19,859		(18,804	)		1,055
Indefinite-lived:
Tradenames		4,670		—			4,670
Balance as of June 30, 2020	$	142,167	$	(93,768	)	$	48,399

	Gross Carrying Value		Accumulated Amortization			Net Carrying Value
Definite-lived:
Customer relationships	$	89,208	$	(50,687	)	$	38,521
Technology		25,106		(19,866	)		5,240
Product development costs		19,911		(18,559	)		1,352
Indefinite-lived:
Tradenames		4,670		—			4,670
Balance as of December 31, 2019	$	138,895	$	(89,112	)	$	49,783

On February 28, 2020, Gentherm acquired the automotive patents and technology of a development-stage technology company for $3,141. The investment was accounted for as an asset acquisition of defensive intangible assets and will be amortized over six years.

On June 19, 2020, Gentherm sold patents from a non-core business for $2,055. The gain on sale of $1,978 was recorded in Other income on the consolidated condensed statements of (loss) income.

In addition to annual impairment testing, which is performed in the fourth quarter of each fiscal year, the Company continuously monitors for events and circumstances that could negatively impact the key assumptions used in determining fair value, including long-term revenue growth projections, profitability, discount rates, recent market valuations from transactions by comparable companies, volatility in the Company's market capitalization, and general industry, market and macroeconomic conditions, requiring interim impairment testing. We are not presently aware of any events or circumstances arising from the COVID-19 pandemic that would require us to revise the carrying value of our assets or liabilities as of June 30, 2020.