use YAML;

for my $company ( sort keys %details_for )
{
    my @trans_details = @{ $details_for{$company} };
    my $comp = $trans_details[0]->{company};
    my $sumcredits;
    $sumcredits += $_->{credits} for @trans_details;

    # Uncomment to see if the "credits" are there as expected.
    # print Dump($details_for{$company});

    # Show the total credits
    printf("%20s --> %.2f\n", $comp, $sumcredits);
}