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