Management completed the annual impairment analysis of goodwill and intangible assets with indefinite lives using a quantitative assessment as of the first day of the fourth quarter of fiscal years 2020, 2019 and 2018, respectively, and determined that recorded amounts were not impaired and that no write-down was necessary.

The following table

summarizes

goodwill by reportable segment:


(in thousands)	Food Safety			Animal Safety			Total
Balance, May 31, 2018	$	40,001		$	59,557		$	99,558
Goodwill acquired		3,796			1,196			4,992
Goodwill and/or currency adjustments (1)		(1,244	)		313			(931	)

Balance, May 31, 2019	$	42,553		$	61,066		$	103,619
Goodwill acquired		6,254			2,095			8,349
Goodwill and/or currency adjustments (1)		(1,592	)		(36	)		(1,628	)

Balance, May 31, 2020	$	47,215		$	63,125		$	110,340

(1)	Includes final purchase price allocation adjustments and currency adjustments for goodwill recorded at international locations.

At May 31, 2020,

non-amortizable

intangible assets included licenses of $569,000, trademarks of $13,424,000 and other intangibles of $1,224,000. At May 31, 2019,

non-amortizable

intangible assets included licenses of $569,000, trademarks of $13,717,000 and other intangibles of $1,224,000.

Amortizable intangible assets consisted of the following and are included in customer-based

intangibles

and other

non-current

assets within the consolidated balance sheets:


(in thousands)	Gross Carrying Amount		Less Accumulated Amortization		Net Carrying Amount
Licenses	$	10,346	$	3,330	$	7,016
Covenants not to compete		706		407		299
Patents		8,509		4,118		4,391
Customer-based intangibles		59,847		29,898		29,949
Other products and service-related intangibles		16,646		6,937		9,709

Balance, May 31, 2020	$	96,054	$	44,690	$	51,364

Licenses	$	9,813	$	3,182	$	6,631
Covenants not to compete		862		542		320
Patents		8,158		3,570		4,588
Customer-based intangibles		57,634		28,017		29,617
Other products and service-related intangibles		16,464		5,524		10,940

Balance, May 31, 2019	$	92,931	$	40,835	$	52,096

Amortization expense for intangibles totaled $6,489,000, $6,309,000 and $6,743,000 in fiscal years 2020, 2019, and 2018, respectively. The estimated amortization expense for each of the five succeeding fiscal years is as follows: $6,573,000 in 2021, $6,445,000 in 2022, $6,006,000 in 2023, $5,700,000 in 2024 and $5,370,000 in 2025. The amortizable intangible assets useful lives are 2 to 20 years for licenses, 3 to 13 years for covenants not to compete, 5 to 25 years for patents, 5 to 20 years for customer-based intangibles and 5 to 20 years for other product and service-related intangibles, which primarily consist of product formulations. All definite-lived intangibles are amortized on a straight-line basis with the exception of definite-lived customer-based intangibles and product and service-related intangibles, which are amortized on either a straight-line or an accelerated basis.