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Stock Incentive Plan - Narrative (Details) - USD ($) |  | 12 Months Ended
--- | --- | ---
Apr. 03, 2017 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Value of shares withheld for taxes |  | $ 1,985,000 | $ 1,109,000 | $ 452,000
Stock issued during period (in shares) |  | 110,000 |  |
Warrants exercised (in shares) |  | 470,000 |  |
Stock issued related to warrants exercised |  | $ 1,477,000 | $ 0 | $ 0
RSAs |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Total compensation cost attributable to shares awarded |  | $ 653,000 |  |
Share vesting period |  | 3 years |  |
Grants in the period (in shares) |  | 51,000 | 52,000 | 49,000
Grants in the period (USD per share) |  | $ 8.73 | $ 12.06 | $ 11.64
Fair value of shares vested in period |  | $ 799,000 | $ 1,261,000 | $ 1,107,000
Vested (in shares) |  | 71,000 |  |
Vested (in usd per share) |  | $ 11.22 |  |
Shares withheld for taxes (in shares) |  | 11,000 | 17,000 | 28,000
Value of shares withheld for taxes |  | $ 140,000 | $ 255,000 | $ 361,000
RSUs |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Total compensation cost attributable to shares awarded |  | $ 2,614,000 |  |
Share vesting period |  | 3 years |  |
Grants in the period (in shares) |  | 169,000 | 261,000 | 248,000
Grants in the period (USD per share) |  | $ 13.52 | $ 12.14 | $ 16.08
Fair value of shares vested in period |  | $ 2,918,000 | $ 1,709,000 | $ 392,000
Vested (in shares) |  | 213,000 |  |
Vested (in usd per share) |  | $ 13.72 |  |
PSUs |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Total compensation cost attributable to shares awarded |  | $ 8,305,000 |  |
Share vesting period |  | 3 years |  |
Grants in the period (in shares) |  | 176,000 | 310,000 | 890,000
Grants in the period (USD per share) |  | $ 14.06 | $ 11.81 | $ 11.64
Fair value of shares vested in period |  | $ 1,620,000 | $ 948,000 |
Vested (in shares) |  | 133,000 |  | 0
Vested (in usd per share) |  | $ 12.20 |  |
RSUs and PSUs |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Shares withheld for taxes (in shares) |  | 123,000 | 74,000 | 8,000
Value of shares withheld for taxes |  | $ 1,845,000 | $ 964,000 | $ 92,000
Warrants to the Lenders Under the Loan Agreement | Loan and Security Agreement |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Warrants, term | 5 years |  |  |
Number of warrants (in shares) | 1,000,000 |  |  |
Warrant exercise price (USD per share) | $ 10.25 |  |  |
Stock Incentive Plan & ESPP |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Total compensation cost attributable to shares awarded |  | $ 11,643,000 | 3,788,000 | $ 3,064,000
Stock Incentive Plan |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Number of shares authorized to issue (in shares) |  |  |  | 1,800,000
Number of shares available for grant (in shares) |  | 0 |  |
Unrecognized compensation cost |  | $ 10,800,000 |  |
Weighted-average recognition period |  | 2 years 3 months 18 days |  |
Stock Incentive Plan | RSAs, RSUs and PSUs |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Total compensation cost attributable to shares awarded |  | $ 11,572,000 | 3,761,000 | $ 3,064,000
ESPP |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Number of shares available for grant (in shares) |  | 748,000 |  |
ESPP | Employee Stock |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Total compensation cost attributable to shares awarded |  | $ 71,000 | $ 27,000 |
Maximum annual contribution per employee |  | 15.00% |  |
Maximum annual contribution amount |  | $ 25,000 |  |
Purchase price of common stock percent |  | 85.00% |  |

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