Yeah, looks good.

By default the GATHER_TABLE_STATS procedure does not gather index stats ... you might like to try that also ...
[code]
begin
dbms_stats.gather_table_stats
(
ownname => 'SCHEMA_NAME',
tabname => 'FLD_DETAIL',
cascade => true
);
end;
/
[code]

If the doesn't work, try collecting column stats for the account_id.