GOODWILL AND INTANGIBLE ASSETS

Intangible assets other than goodwill are amortized over their estimated useful lives on either a straight-line basis or proportionately to the benefit being realized. Useful lives range from two to eighteen years. The Company periodically reviews the estimated useful lives of our intangible assets and review such assets or asset groups for impairment whenever events or changes in circumstances indicate that the carrying value of the assets or asset groups may not be recoverable. If an intangible asset or asset group is considered to be impaired, the amount of the impairment will equal the excess of the carrying value over the fair value of the asset.

Goodwill is not amortized, but rather, is tested for impairment annually or more frequently if impairment indicators arise. Goodwill represents the excess of the purchase price over the fair value of the net tangible and identifiable intangible assets acquired in each business combination.

The changes in the carrying amount of goodwill for the three months ended August 31, 2018 were as follows:



(in thousands)
Goodwill balance at June 1, 2018	$	361,252
Additions for BioSentry acquisition (Note 2)	21,740
Goodwill balance at August 31, 2018	$	382,992

The Company's annual testing for impairment of goodwill was completed as of December 31, 2017. The Company operates as a single operating segment with one reporting unit and consequently evaluates goodwill for impairment based on an evaluation of the fair value of the Company as a whole. The Company determines the fair value of the reporting unit based on the market valuation approach and concluded that it was not more-likely-than-not that the fair value of the Company's reporting unit was less than its carrying value.

Even though the Company determined that there was no goodwill impairment as of December 31, 2017, the future occurrence of a potential indicator of impairment, such as a significant adverse change in legal, regulatory, business or economic conditions or a more-likely-than-not expectation that the reporting unit or a significant portion of the reporting unit will be sold or disposed of, would require an interim assessment for the reporting unit prior to the next required annual assessment as of December 31, 2018. The Company continued to assess for potential impairment through August 31, 2018 and noted no events that would be considered a triggering event.

Intangible assets consisted of the following:



	August 31, 2018
	Gross carrying value		Accumulated amortization			Net carrying value
(in thousands)
Product technologies	$	160,973	$	(71,204	)	$	89,769
Customer relationships	58,917		(24,199		)	34,718
Trademarks	30,100		(12,411		)	17,689
Licenses	5,752		(4,527		)	1,225
Distributor relationships	1,250		(457		)	793
	$	256,992	$	(112,798	)	$	144,194



	May 31, 2018
	Gross carrying value		Accumulated amortization			Net carrying value
(in thousands)
Product technologies	$	147,175	$	(68,880	)	$	78,295
Customer relationships	56,428		(23,237		)	33,191
Trademarks	28,400		(11,809		)	16,591
Licenses	5,752		(4,357		)	1,395
Distributor relationships	1,250		(412		)	838
	$	239,005	$	(108,695	)	$	130,310

Amortization expense for the three months ended August 31, 2018 and 2017 was $4.1 million and $4.1 million, respectively.

Expected future amortization expense related to the intangible assets is as follows:



(in thousands)
Remainder of 2019	$	13,457
2020	16,280
2021	15,121
2022	14,236
2023	13,786
2024 and thereafter	71,314
	$	144,194