INTANGIBLE ASSETS

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets, Net consisted of the following:


	December 31,
	2019		2018
Intangible assets:
Finite-lived intangible assets	$	652,734	$	307,995
Indefinite-lived intangible assets	—		326,359
Gross intangible assets:	652,734		634,354
Less: Accumulated amortization	(196,154)		(142,546)
Net carrying value	$	456,580	$	491,808

Finite-Lived Intangible Assets

The following table summarizes the carrying value and estimated remaining life of the Company’s finite-lived intangible assets as of December 31, 2019:


	Net Balance		Average Remaining Life
Acquired intellectual property	$	406,058	7.8 years
Repurchased royalty rights	26,438		3.9 years
Technology transfer	23,078		Not applicable (1)
Other	1,006		1.2 - 4.6 years
Total	$	456,580

(1)The technology transfer intangible asset has not yet been placed into service.

As of December 31, 2019, the estimated future amortization expense associated with the Company’s finite-lived intangible assets, exclusive of the technology transfer asset that has not been placed into service, was as follows:


Fiscal Year	Amount
2020	$	62,887
2021	61,963
2022	61,939
2023	61,311
2024	55,036
Thereafter	130,366
	$	433,502

Indefinite-Lived Intangible Assets

The Company’s indefinite-lived intangible assets were $326.4 million as of December 31, 2018 and consisted of IPR&D related to the Palynziq rights in Europe. During the second quarter of 2019, these indefinite-lived intangible assets were reclassified

to definite-lived as the underlying IPR&D was placed into service upon receiving European regulatory approval for Palynziq. The Company will straight-line the amortization expense for the underlying IPR&D over its estimated useful life of nine years.

In 2019 and 2018, the Company received $25.0 million and $50.0 million, respectively, due to the achievement by a third party of development and regulatory milestones and commercial sales milestones related to a previously sold intangible asset, which the Company recorded as a gain on the sale of intangible assets in the Consolidated Statements of Operations.

In December 2017, the Company sold the Rare Pediatric Disease Priority Review Voucher (PRV) it received from the Food and Drug Administration in connection with the U.S. approval of Brineura. In exchange for the voucher, the Company received $125.0 million in proceeds from the sale of the PRV, which was recognized as a gain on the sale of intangible asset as the PRV did not have a carrying value on the Company’s Consolidated Balance Sheet at the time of sale.

In the fourth quarter of 2017, the Company recognized an impairment charge of $5.8 million related to other acquired IPR&D assets recorded in Intangible Asset Amortization and Contingent Consideration on the Company's Consolidated Statements of Operations.