Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Intangible Assets

Intangible asset balances as of March 31, 2018 and December 31, 2017 are as follows:

	March 31, 2018
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value
	(in thousands)
Developed technology - lomitapide	$	42,300	$	(5,246	)	$	37,054
Developed technology - metreleptin	210,158		(28,214		)	181,944
Total intangible assets	$	252,458	$	(33,460	)	$	218,998

	December 31, 2017
	Gross Carrying Value		Accumulated Amortization			Net Carrying Value
	(in thousands)
Developed technology - lomitapide	$	42,300	$	(4,262	)	$	38,038
Developed technology - metreleptin	210,158		(22,924		)	187,234
Total intangible assets	$	252,458	$	(27,186	)	$	225,272

Estimated Future Amortization Expense of Acquired Intangibles

As of March 31, 2018, the estimated amortization expense related to intangibles for future periods is as follows: 

	Amount
Years Ending December 31,	(in thousands)
2018 (remaining 9 months)	$	18,821
2019	25,095
2020	25,095
2021	25,095
2022	25,095
Thereafter	99,797
Total intangible assets subject to amortization	$	218,998