Error 8115, Level 16, State 2

[aromanocohen]

i don't know how, but a field called "IMPORTE" of type DECIMAL in one of my tables has this huge number that has 18 digits to the left of the dot in one of the records:

659,999,999,999,999,993.00

When I trie to restore a backup of the database in my ERP it prompts an overflow error in a decimal, so I tried to modify the record directly with the Microsoft SQL QUERY ANALIZER with a script, but I receive the
following error:

SCRIPT:
UPDATE [Kanan Hit, S.A. de C.V.$Mov. contabilidad]
SET Importe = 1.00
WHERE ([Nº mov.] = 2269137)

Error:
Server: Msg 8115, Level 16, State 2, Procedure Kanan Hit, S.A. de C.V.$Mov. contabilidad_TG, Line 199

I don't know how the numbered entered in the field because by definition, a decimal field can only have 17 digits, and the number has 18.

thank you. :( :(