Overlapping ranges

I have a large table of access logs to an application.

I want is to find all rows that overlap startdate and enddate with any
other rows.

The query below seems to work, but does not finish unless I specify a
single id.

select distinct a1.id
from t_access a1,
        t_access a2
where tstzrange(a1.startdate, a1.enddate) &&
      tstzrange(a2.startdate, a2.enddate)