Investments and Fair Value of Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2017

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 September 30, 2017 and December 31, 2016, and the corresponding amounts of unrealized gains and losses recognized in accumulated other comprehensive income (“AOCI”):

(Dollars in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
September 30, 2017
Cash equivalents:
Money market funds		2,631		—		—			2,631
Short-term investments:
Certificates of Deposit		980		—		—			980
Commercial paper		4,290		—		—			4,290
U.S. government securities		5,001		—		(4	)		4,997
U.S. government agency securities		2,500		—		—			2,500
Total Assets at Fair Value	$	15,402	$	—	$	(4	)	$	15,398

(Dollars in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
December 31, 2016
Cash equivalents:
Money market funds	$	1,549	$	—	$	—		$	1,549
Short-term investments:
Certificates of Deposit		3,049		—		(2	)		3,047
Commercial paper		21,248		—		—			21,248
U.S. government securities		19,267		—		(9	)		19,258
U.S. government agency securities		5,000		—		(6	)		4,994
Long-term investments:
U.S. government securities		2,500		—		(2	)		2,498
Total Assets at Fair Value	$	52,613	$	—	$	(19	)	$	52,594

Summary of Fair Value of Available-for-Sale Investments

The fair value of the available-for-sale investments at September 30, 2017 and December 31, 2016 were as follows:

	Fair Value Measurements at September 30, 2017
(Dollars in thousands)	Level 1		Level 2		Level 3		Total
Assets at Fair Value
Cash equivalents:
Money market funds		2,631		—		—		2,631
Short-term investments:
Certificates of Deposit		—		980		—		980
Commercial paper		—		4,290		—		4,290
U.S. government securities		4,997		—		—		4,997
U.S. government agency securities		—		2,500		—		2,500
Total Assets at Fair Value	$	7,628	$	7,770	$	—	$	15,398

	Fair Value Measurements at December 31, 2016
(Dollars in thousands)	Level 1		Level 2		Level 3		Total
Assets at Fair Value
Cash equivalents:
Money market funds	$	1,549	$	—	$	—	$	1,549
Short-term investments:
Certificates of Deposit		—		3,047		—		3,047
Commercial paper		—		21,248		—		21,248
U.S. government securities		19,258		—		—		19,258
U.S. government agency securities		—		4,994		—		4,994
Long-term investments:
U.S. government securities		2,498		—		—		2,498
Total Assets at Fair Value	$	23,305	$	29,289	$	—	$	52,594