There's likely a much simpler solution, but it's Saturday morning and I'm not quite "clicking" 😉
Try this:
with TermCTE (Doc, ProdType, Term, TermType) as
(Select
Doc,
ProdType,
Term,
TermType = case when Term = 1 then 'Yr'
when Term = 12 then 'Mth'
else 'Other'
end
from Table_name)
, sumCTE (Doc, ProdType, Term, YrSum, MthSum)
as
(Select
Doc,
ProdType,
Term,
YrSum = (Select sum(Term) from TermCTE where TermType = 'Yr'),
MthSum = (Select sum(Term) from TermCTE where TermType = 'Mth')
from TermCTE)
Select
Doc,
ProdType,
Term,
YrSum,
MthSum,
Sum_of_both = YrSum + MthSum
from sumCTE