Fair Value of Financial Instruments (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Fair Value of Financial Instruments

Schedule of estimated fair values of financial instruments outstanding

The estimated fair values of financial instruments outstanding were (in thousands):

	September 30, 2017
			Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Cash and cash equivalents	$	2,784	$	—	$	—	$	2,784

	December 31, 2016
			Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Cash and cash equivalents	$	8,766	$	—	$	—	$	8,766
Short-term investments:
U.S. government-sponsored enterprise bonds	$	762	$	—	$	—	$	762
Corporate notes		240		—		—		240
Total short-term investments	$	1,002	$	—	$	—	$	1,002

The estimated fair values of financial instruments outstanding were (in thousands):

	December 31, 2016
			Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Cash and cash equivalents	$	8,766	$	—	$	—	$	8,766
Short-term investments:
U.S. government-sponsored enterprise bonds	$	762	$	—	$	—	$	762
Corporate notes		240		—		—		240
Total short-term investments	$	1,002	$	—	$	—	$	1,002

	December 31, 2015
			Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Cash and cash equivalents	$	5,640	$	—	$	—	$	5,640
Short-term investments:
U.S. government-sponsored enterprise bonds	$	6,243	$	—	$	—	$	6,243
Municipal bonds		200		—		—		200
Corporate notes		8,171		—		(16)		8,155
Total short-term investments	$	14,614	$	—	$	(16)	$	14,598

Schedule of estimated fair values of available-for-sale securities with unrealized losses

The estimated fair values of available-for-sale securities with unrealized losses as of December 31, 2015 were (in thousands):

	December 31, 2015
			Unrealized		Fair
	Cost		Losses		Value
Short-term investments:
Corporate notes	$	8,171	$	(16)	$	8,155
Total short-term investments	$	8,171	$	(16)	$	8,155

Schedule of fair value hierarchy for financial assets (cash equivalents and investments)

The following table represents the Company’s fair value hierarchy for its financial assets (cash equivalents and investments) as of September 30, 2017 and December 31, 2016 (in thousands):

	September 30, 2017
	Fair Value		Level 1		Level 2		Level 3
Money market funds	$	620	$	620	$	—	$	—

	December 31, 2016
	Fair Value		Level 1		Level 2		Level 3
Money market funds	$	84	$	84	$	—	$	—
U.S. government-sponsored enterprise bonds		3,767		—		3,767		—
Municipal bonds		4,027		—		4,027		—
Corporate notes		480		—		480		—
Total assets	$	8,358	$	84	$	8,274	$	—

The following table represents the Company’s fair value hierarchy for its financial assets (cash equivalents and investments) as of December 31, 2016 and 2015 (in thousands):

	December 31, 2016
	Fair Value		Level 1		Level 2		Level 3
Money market funds	$	84	$	84	$	—	$	—
U.S. government-sponsored enterprise bonds		3,767		—		3,767		—
Municipal bonds		4,027		—		4,027		—
Corporate notes		480		—		480		—
Total assets	$	8,358	$	84	$	8,274	$	—

	December 31, 2015
	Fair Value		Level 1		Level 2		Level 3
Money market funds	$	2,238	$	2,238	$	—	$	—
U.S. government-sponsored enterprise bonds		7,525		—		7,525		—
Municipal bonds		200		—		200		—
Corporate notes		8,255		—		8,255		—
Certificates of deposit		240		—		240		—
Total assets	$	18,458	$	2,238	$	16,220	$	—

Schedule of cost and fair value of investments based on maturity groups

Cost and fair value of investments based on two maturity groups were (in thousands):

	December 31, 2016
			Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Due within 1 year	$	1,002	$	—	$	—	$	1,002

	December 31, 2015
			Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Due within 1 year	$	14,614	$	—	$	(16)	$	14,598