Changes in the carrying amount of goodwill were as follows:


(dollar amounts in thousands)	Mobile Modular			Adler Tanks (Discontinued)			Total
Balance at December 31, 2021	$	106,491		$	25,902		$	132,393
Changes to Design Space purchase accounting		(88	)		—			(88	)
Balance at December 31, 2022		106,403			25,902			132,305
Goodwill acquired through business combination		216,821			—			216,821
Derecognition of goodwill divested		—			(25,902	)		(25,902	)
Balance at December 31, 2023	$	323,224		$	—		$	323,224

Intangible assets from continuing operations consist of the following:


(dollar amounts in thousands)	Estimated useful life in years	Average remaining life in years	Cost	Accumulated amortization	Net book value
December 31, 2023
Customer relationships	8 to 11	7.8	$73,217	$(17,003)	$56,214
Non-compete agreements	5	3.7	10,556	(3,141)	7,415
Trade name	0.75 to 8	5.3	2,000	(1,212)	788
Total amortizing			85,773	(21,356)	64,417
Trade name - non-amortizing	Indefinite		171	—	171
Total			$85,944	$(21,356)	$64,588

December 31, 2022
Customer relationships	8 to 11	6.3	$50,284	$(18,098)	$32,186
Non-compete agreements	5	3.2	3,296	(1,159)	2,137
Customer backlog	—	—	1,900	(1,900)	—
Trade name	8	6.3	1,200	(263)	937
Total amortizing			56,680	(21,420)	35,260
Trade name - non-amortizing	Indefinite		5,871	—	5,871
Total			$62,551	$(21,420)	$41,131

The Company assesses potential impairment of its goodwill and intangible assets when there is evidence that events or circumstances have occurred that would indicate the recovery of an asset’s carrying value is unlikely. The Company also assesses potential impairment of its goodwill and intangible assets with indefinite lives on an annual basis regardless of whether there is evidence of impairment. If indicators of impairment were to be present in intangible assets used in operations and future discounted cash flows were not expected to be sufficient to recover the asset’s carrying amount, an impairment loss would be charged to expense in the period identified. The amount of an impairment loss that would be recognized is the excess of the asset’s carrying value over its fair value. Factors the Company considers important, which may cause impairment include, among others, significant changes in the manner of use of the acquired asset, negative industry or economic trends, and significant underperformance relative to historical or projected operating results. The Company last conducted a qualitative analysis of its goodwill and intangible assets in the fourth quarter 2023, with no indicators of impairment. In addition, no impairment triggering events occurred during the year ended December 31, 2023. Determining fair value of a reporting unit is judgmental and involves the use of significant estimates and assumptions. The

Company bases its fair value estimates on assumptions that it believes are reasonable but are uncertain and subject to changes in market conditions.

Intangible assets with finite useful lives are amortized over their respective useful lives. Amortization expense in the years ended December 31, 2023, 2022 and 2021 was $10.7 million, $5.9 million and $5.9 million, respectively. Based on the carrying values at December 31, 2023 and assuming no subsequent impairment of the underlying assets, the annual amortization is expected to be $10.3 million in 2024, $10.2 million in 2025, $9.8 million in 2026, $9.6 million in 2027 and $8.2 million in 2028. For information on intangible assets from discontinued operations refer to Note 5.