Oracle sql to generate combinations for each row id

Question

I have the following table

mydata:

ID  NUMBERS
1   1,2
2   1,2,3,4,5
3   1,2,3

My ultimate goal is to generate the following result:

ID  Num
1   1
1   2
2   1
2   2
2   3
2   4
2   5
3   1
3   2
3   3

e.g. all the combinations for each id with a corresponding numbers

now... I came up with the following query

with mydata as (
select 1 as id, '1,2' as numbers from dual
union
select 2 as id, '1,2,3,4,5' as numbers from dual
union 
select 3 as id, '1,2,3' as numbers from dual
)
SELECT distinct  id,TRIM(REGEXP_SUBSTR(numbers, '[^,]+', 1, level)) lv
   FROM (
    select id, numbers
    from mydata 
  )
    CONNECT BY  level <= REGEXP_COUNT(numbers, '[^,]+')
  order by id

Without the distinct - the above query gives 66 repetitive combinations instead of 10 combinations needed (so for large data set - it will get slow..)

I wonder, is it a correct way to achieve this and is there any better and more efficient way to get the desired result.

Thanks.