Convert variable into array in php - php

Question

When I use <pre>to display my variable echo $value_detail_final;
it displays a proper file like this
{
"companies": [
{
"id": "4127303000000527195",
"company_name": "235 St Georges Landowning Trust & Australian City Properties Pty Ltd"
},
{
"id": "4127303000004495043",
"company_name": "Bourke Junction No 1 Pty Ltd"
},
{
"id": "4127303000000527189",
"company_name": "Brookfield Commercial Operations Pty Ltd"
}
]
}
But when I use something like this $value_detail_final[0] it displays {
if $value_detail_final[1] its ", its like displaying each character on my variable .
even foreach doesnt work, by the way this is from json file and I use json_decode file.
How can I able to put each of the id and company_name into a variable so I can use them ?
This is how I decode my json file based on the given sturcture
$jsondata = file_get_contents("response.json");
$array = json_decode($jsondata,true);
echo "<pre>";
foreach ($array as $key => $value) {
// echo "Key:".$key."<br>";
if($key=='details')
{
foreach ($value as $key_detail => $detail)
{
if($key_detail=='userMessage')
{
foreach ($detail as $key_detail_final => $value_detail_final)
{
print_r($value_detail_final);
}
}
}
}
}