SHAREHOLDERS' EQUITY, Preferred Shares (Q1) (Details) - $ / shares |
Mar. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
|---|---|---|---|
| SHAREHOLDERS' EQUITY [Abstract] | |||
| Preference shares, shares authorized (in shares) | 1,000,000 | 1,000,000 | 1,000,000 |
| Preference shares, par value (in dollars per share) | $ 0.0001 | $ 0.0001 | $ 0.0001 |
| Preference shares, shares issued (in shares) | 0 | 0 | 0 |
| Preference shares, shares outstanding (in shares) | 0 | 0 | 0 |