```python
from fastapi import FastAPI, Body
import asyncio
import helpers

app = FastAPI()

@app.post("/documents", status_code=201)
async def create_document(name: str = Body(...), text: str = Body(...)):
    loop = asyncio.get_event_loop()
    bytes_written = await loop.run_in_executor(None, helpers.save_document, name, text)
    return {"bytes": bytes_written}
```