Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2017

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured at Fair Value on Recurring Basis

Assets and liabilities measured at fair value that have recurring measurements are shown below (in thousands):

			Fair Value Measurement at Reporting Date Using
Description	Balance as of September 30, 2017		Quoted Prices in Active Markets for IdenticalAssets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Money market funds	$	33,917	$	33,917	$	—	$	—
U.S. Treasury securities		24,990		—		24,990		—
Total assets measured at fair value	$	58,907	$	33,917	$	24,990	$	—
Liabilities:
Contingent consideration - long-term	$	8,400	$	—	$	—	$	8,400
Convertible debt - 2017 Exchange Notes		17,034		—		—		17,034
Convertible debt - 2016 Notes		129,200		—		—		129,200
Total liabilities measured at fair value	$	154,634	$	—	$	—	$	154,634

			Fair Value Measurement at Reporting Date Using
Description	Balance as of December 31, 2016		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Financial instruments owned:
Money market funds	$	65,081	$	65,081	$	—	$	—
U.S. Treasury securities		100,005		—		100,005		—
Corporate debt securities		1,499				1,499
Total assets measured at fair value	$	166,585	$	65,081	$	101,504	$	—
Liabilities:
Contingent consideration - current	$	15,000	$	—	$	—	$	15,000
Contingent consideration - long-term		6,800						6,800
Convertible debt		101,900		—		—		101,900
Total liabilities measured at fair value	$	123,700	$	—	$	—	$	123,700

Changes in Level 3 Liabilities Measured at Fair Value

The following table presents changes in Level 3 liabilities measured at fair value for the nine months ended September 30, 2017 (in thousands):

Contingent Consideration—December 31, 2016	$	21,800
Payment to Takeda	$	(15,000	)
Change in fair value of contingent consideration (recognized in Net loss)		1,600
Contingent Consideration at fair value – September 30, 2017	$	8,400
2017 Exchange Notes—December 31, 2016	$	—
Transfer from Level 2 to Level 3 - April 1, 2017		21,866
Exchange Notes conversions (recognized in equity)		(894	)
Change in fair value of 2017 Exchange Notes (recognized in Net loss)		(3,938	)
2017 Exchange Notes at fair value – September 30, 2017	$	17,034
Convertible debt - 2016 Notes—December 31, 2016	$	101,900
Change in fair value of convertible debt (recognized in Net loss)		27,300
Convertible debt - 2016 Notes at fair value – September 30, 2017	$	129,200