2.	Goodwill and Other Intangible Assets

Management has 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 2018, 2017 and 2016, respectively, and determined that recorded amounts were not considered 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, 2016	$	26,889		$	61,617		$	88,506
Goodwill acquired		19,051			—			19,051
Goodwill adjustments and/or currency (1)		(20	)		(2,778	)		(2,798	)

Balance, May 31, 2017	$	45,920		$	58,839		$	104,759
Goodwill acquired		—			757			757
Goodwill adjustments and/or currency (1)		(5,919	)		(39	)		(5,958	)

Balance, May 31, 2018	$	40,001		$	59,557		$	99,558

(1)	Includes final purchase price allocation adjustment.

At May 31, 2018, non-amortizable intangible assets included licenses of $569,000, trademarks of $12,989,000 and other intangibles of $1,224,000. At May 31, 2017, non-amortizable intangible assets included licenses of $569,000, trademarks of $12,530,000 and other intangibles of $1,224,000.

Amortizable intangible assets consisted of the following and are included in customer-based intangible and other non-current assets within the consolidated balance sheets:


(in thousands)	Gross Carrying Amount		Less Accumulated Amortization		Net Carrying Amount
Licenses	$	9,491	$	2,523	$	6,968
Covenants not to compete		801		483		318
Patents		9,693		5,013		4,680
Customer-based intangibles		56,420		24,579		31,841
Other products and service-related intangibles		15,299		4,451		10,848

Balance, May 31, 2018	$	91,704	$	37,049	$	54,655

Licenses	$	5,989	$	2,011	$	3,978
Covenants not to compete		1,208		309		899
Patents		9,304		4,601		4,703
Customer-based intangibles		56,829		20,846		35,983
Other products and service-related intangibles		12,065		3,010		9,055

Balance, May 31, 2017	$	85,395	$	30,777	$	54,618

Amortization expense for intangibles totaled $6,743,000, $5,908,000 and $4,730,000 in fiscal years 2018, 2017, and 2016, respectively. The estimated amortization expense for each of the five succeeding fiscal years is as follows: $6,179,000 in 2019, $5,865,000 in 2020, $5,435,000 in 2021, $5,048,000 in 2022 and $4,702,000 in 2023. The amortizable intangible assets useful lives are 2 to 20 years for licenses, 5 to 13 years for covenants not to compete, 5 to 25 years for patents, 5 to 20 years for customer-based intangibles and 2 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.