Series idxmin() TypeError?Need change type to 'float'
i'm using idxmin() on a series, which is like:
```
    ltc: 
    调度报障工单号
    DD182103227    5
                  ..
    DD082104265    5
    Name: 供电所, Length: 848, dtype: Int64
```
However, when using:
`    ltc.idxmin()`

i got an error:
`    TypeError: argmin() takes 1 positional argument but 2 were given`

when using:
`  ltc.astype('float').idxmin()`

i got the right answer:
    'DD092104104'

But the api doesn't say that idxmin() can only use on float data.Why?