Purchase Analysis SQL ERROR: numeric field overflow

addons/purchase/report/purchase_report.py line74:

cr.execute("""
            create or replace view purchase_report as (
                select
                    min(l.id) as id,
                    s.date_order as date,
                    to_char(s.date_order, 'YYYY') as name,
                    to_char(s.date_order, 'MM') as month,
                    to_char(s.date_order, 'YYYY-MM-DD') as day,
                    s.state,
                    s.date_approve,
                    date_trunc('day',s.minimum_planned_date) as expected_date,
                    s.partner_address_id,
                    s.dest_address_id,
                    s.pricelist_id,
                    s.validator,
                    s.warehouse_id as warehouse_id,
                    s.partner_id as partner_id,
                    s.create_uid as user_id,
                    s.company_id as company_id,
                    l.product_id,
                    t.categ_id as category_id,
                    (case when u.uom_type not in ('reference') then
                            (select id from product_uom where uom_type='reference' and category_id = 1)
                    else
                        u.id
                    end) as product_uom,
                    s.location_id as location_id,
                    sum(l.product_qty/u.factor) as quantity,
                    extract(epoch from age(s.date_approve,s.date_order))/(24*60*60)::decimal(18,2) as delay,
                    extract(epoch from age(l.date_planned,s.date_order))/(24*60*60)::decimal(18,2) as delay_pass,
                    count(*) as nbr,
                    (l.price_unit*l.product_qty*u.factor)::decimal(18,2) as price_total,
                    avg(100.0 * (l.price_unit*l.product_qty*u.factor) / NULLIF(t.standard_price*l.product_qty*u.factor, 0.0))::decimal(18,2) as negociation,

                    sum(t.standard_price*l.product_qty*u.factor)::decimal(18,2) as price_standard,
                    (sum(l.product_qty*l.price_unit)/NULLIF(sum(l.product_qty*u.factor),0.0))::decimal(18,2) as price_average
                from purchase_order s
                    left join purchase_order_line l on (s.id=l.order_id)
                        left join product_product p on (l.product_id=p.id)
                            left join product_template t on (p.product_tmpl_id=t.id)
                    left join product_uom u on (u.id=l.product_uom)
                where l.product_id is not null
                group by
                    s.company_id,
                    s.create_uid,
                    s.partner_id,
                    l.product_qty,
                    u.factor,
                    s.location_id,
                    l.price_unit,
                    s.date_approve,
                    l.date_planned,
                    l.product_uom,
                    date_trunc('day',s.minimum_planned_date),
                    s.partner_address_id,
                    s.pricelist_id,
                    s.validator,
                    s.dest_address_id,
                    l.product_id,
                    t.categ_id,
                    s.date_order,
                    to_char(s.date_order, 'YYYY'),
                    to_char(s.date_order, 'MM'),
                    to_char(s.date_order, 'YYYY-MM-DD'),
                    s.state,
                    s.warehouse_id,
                    u.uom_type,
                    u.category_id,
                    u.id
            )
        """)

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ERROR: numeric field overflow
DETAIL: A field with precision 16, scale 2 must round to an absolute value less than 10^14.

********** Error **********

ERROR: numeric field overflow
SQL state: 22003
Detail: A field with precision 16, scale 2 must round to an absolute value less than 10^14.

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If i replace in the code : decimal(16,2) --> decimal(18,2)

It's working good.