Intangible assets (Tables)

12 Months Ended

Dec. 31, 2021

Goodwill And Intangible Assets Disclosure [Abstract]

Intangible assets are recorded at cost, or when acquired as a part of a business combination, at estimated fair value, such as for in-process research and development (“IPR&D”) assets. These assets are amortized on a straight-line basis over the useful lives of the assets, which the Company believes is materially consistent with the pattern of economic benefit provided by the assets.

		December 31,
(U.S. Dollars, in thousands)	Weighted Average Amortization Period	2021			2020
Cost
Patents	10 years	$	44,561		$	50,326
Developed technology	10 years		43,979			44,334
IPR&D	Indefinite		300			300
Customer relationships	7 years		15,621			15,685
License and other	8 years		18,924			16,941
Trademarks—finite lived	10 years		1,839			1,812
	9 years		125,224			129,398
Accumulated amortization
Patents		$	(41,408	)	$	(46,272	)
Developed technology			(13,409	)		(8,925	)
Customer relationships			(4,520	)		(2,095	)
License and other			(12,528	)		(11,006	)
Trademarks—finite lived			(693	)		(583	)
			(72,558	)		(68,881	)
Intangible assets, net		$	52,666		$	60,517

Schedule of Future Amortization Expense

Future amortization expense for intangible assets is estimated as follows:

(U.S. Dollars, in thousands)	Amortization
2022	$	9,376
2023		8,692
2024		8,254
2025		7,252
2026		6,215
Thereafter		12,577
Total finite-lived intangible assets, net	$	52,366
Indefinite-lived intangible assets, net		300
Intangible assets, net	$	52,666