Liquidity and Going Concern - Narrative (Details) - USD ($) |
1 Months Ended | |||||
|---|---|---|---|---|---|---|
Jul. 31, 2018 |
Jun. 30, 2018 |
Dec. 31, 2017 |
Jun. 30, 2017 |
Dec. 31, 2016 |
May 19, 2015 |
|
| Liquidity and Going Concern | ||||||
| Accumulated deficit | $ 230,592,000 | $ 228,346,000 | ||||
| Cash | 1,779,000 | $ 2,807,000 | $ 1,611,000 | $ 7,839,000 | ||
| Shelf Registration | ||||||
| Liquidity and Going Concern | ||||||
| Aggregate securities authorized | $ 50,000,000.0 | |||||
| Aggregate securities sold | $ 3,100,000 | |||||
| Subsequent Event | ||||||
| Liquidity and Going Concern | ||||||
| Shares Sold In Rights Offering | $ 2,200,000 |