Investments and Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2019

Investments And Fair Value Of Financial Instruments [Abstract]

Summary of Amortized Cost and Fair Value of the Available-For-Sale Investment Securities Portfolio

The following tables summarize the amortized cost and fair value of the available-for-sale investment securities portfolio at March 31, 2019 and December 31, 2018, and the corresponding amounts of unrealized gains and losses recognized in accumulated other comprehensive income:

(Dollars in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
March 31, 2019
Cash equivalents:
Money market funds	$	6,283	$	—	$	—	$	6,283
Corporate securities		599		—		—		599
Commercial paper		3,044		—		—		3,044
Short-term investments:
Corporate securities		1,248		—		—		1,248
Treasury Bills		997		—		—		997
Commercial paper		5,110		—		—		5,110
Total Assets at Fair Value	$	17,281	$	—	$	—	$	17,281

(Dollars in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses		Estimated Fair Value
December 31, 2018
Cash equivalents:
Money market funds	$	9,902	$	—	$	—	$	9,902
Commercial paper		1,345		—		—		1,345
Short-term investments:
Corporate Securities		656		—		—		656
Treasury Bills		1,195		—		—		1,195
Commercial paper		6,776		—		—		6,776
U.S. government securities		1,198		—		—		1,198
Total Assets at Fair Value	$	21,072	$	—	$	—	$	21,072

Summary of Fair Value of Financial Assets

The following table sets forth the fair value of the Company’s financial assets as of March 31, 2019 and December 31, 2018:  

	Fair Value Measurements at March 31, 2019
(Dollars in thousands)	Level 1		Level 2		Level 3		Total
Assets at Fair Value
Cash equivalents:
Money market funds	$	6,283	$	—	$	—	$	6,283
Corporate securities		—		599		—		599
Commercial paper		—		3,044		—		3,044
Short-term investments:
Corporate securities		—		1,248		—		1,248
Treasury Bills		997		—		—		997
Commercial paper		—		5,110		—		5,110
Total Assets at Fair Value	$	7,280	$	10,001	$	—	$	17,281

	Fair Value Measurements at December 31, 2018
(Dollars in thousands)	Level 1		Level 2		Level 3		Total
Assets at Fair Value
Cash equivalents:
Money market funds	$	9,902	$	—	$	—	$	9,902
Commercial paper		—		1,345		—		1,345
Short-term investments:
Corporate Securities		—		656		—		656
Treasury Bills		1,195		—		—		1,195
Commercial paper		—		6,776		—		6,776
U.S. government securities		1,198		—		—		1,198
Total Assets at Fair Value	$	12,295	$	8,777	$	—	$	21,072

Summary of Changes in Fair Value of Liabilities

The following table sets forth the establishment of these liabilities, as well as a summary of the changes in the fair value (in thousands):

	(Level 3)
(Dollars in thousands)	Common Stock Warrant Liability - Purchase Agreement		Common Stock Warrant Liability - June Offering		Total
Balance as of December 31, 2018	$	2,354	$	2,729	$	5,083
Change in fair value		3,970		4,525		8,495
Balance as of March 31, 2019	$	6,324	$	7,254	$	13,578