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Marketable Securities and Fair Value Disclosures | 12 Months Ended
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Dec. 31, 2018
Marketable Securities And Fair Value Disclosures [Abstract] |
Marketable Securities and Fair Value Disclosures | (3) Marketable Securities and Fair Value Disclosures There were no marketable securities as of December 31, 2018. Marketable securities consisted of the following as of December 31, 2017 (in thousands):
| December 31, 2017 |
|  |  |  |  | Gross |  |  | Gross |  |  |  |  |
| Amortized |  |  | Unrealized |  |  | Unrealized |  |  | Fair |
| Cost |  |  | Gains |  |  | Losses |  |  | Value |
Short-term available-for-sale securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate bonds | $ | 3,052 |  |  | $ | — |  |  | $ | (2 | ) |  | $ | 3,050 |
Total | $ | 3,052 |  |  | $ | — |  |  | $ | (2 | ) |  | $ | 3,050 |
Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). Inputs used to measure fair value are classified into the following hierarchy:
| • | Level 1—Unadjusted quoted prices in active markets for identical assets or liabilities. The Company’s Level 1 assets consist of money market investments. The Company does not have any Level 1 liabilities.
| • | Level 2—Unadjusted quoted prices in active markets for similar assets or liabilities; unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active; or inputs other than quoted prices that are observable for the asset or liability. The Company’s Level 2 assets consist of corporate bonds and commercial paper securities. The Company does not have any Level 2 liabilities.
| • | Level 3—Unobservable inputs for the asset or liability. The Company does not have any Level 3 assets or liabilities.
The following table identifies the Company’s assets that were measured at fair value on a recurring basis (in thousands):
| Balance |  |  | Level 1 |  |  | Level 2 |  |  | Level 3 |
December 31, 2018 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market | $ | 6,529 |  |  | $ | 6,529 |  |  | $ | — |  |  | $ | — |
Total | $ | 6,529 |  |  | $ | 6,529 |  |  | $ | — |  |  | $ | — |
December 31, 2017 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market | $ | 8,189 |  |  | $ | 8,189 |  |  | $ | — |  |  | $ | — |
Corporate bonds |  | 3,725 |  |  |  | — |  |  |  | 3,725 |  |  |  | — |
Total | $ | 11,914 |  |  | $ | 8,189 |  |  | $ | 3,725 |  |  | $ | — |
As of December 31, 2018 and 2017, the Company had $6.5 million and $8.9 million, respectively, of cash equivalents consisting of money market funds, and corporate bonds in 2017, with original maturities of 90 days or less. The Company has the ability to liquidate these investments without restriction. The Company determines fair value for these money market funds and equity securities with Level 1 inputs through quoted market prices. There were no transfers between any fair value hierarchy levels in 2018 or 2017. Fair Value of Other Financial Instruments The carrying amount of other financial instruments, including accounts payable, approximated fair value due to their short maturities. As of December 31, 2018 and 2017, the Company did not have any debt outstanding.

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