You can actually copy the 18-character ID to your clipboard in 15 seconds, using only your web browser. If this video demo goes a bit too fast, below are the written steps:
- Open the Developer Console
- In the bottom panel, open the Query Editor tab
- For the query, write: SELECT Id FROM Organization
- Click the Execute button. The keyboard shortcut is to press Tab, Tab, Enter.
- Double-click the single ID returned to select the 18-character value
- Copy and paste as needed