How to apply an x-path into an array.

below is the sample JSON response, I want to get the documentid whose "subcategory" : "Loans" only

i tried below, didn't work out.
//documents/documentId[subcategory="Loans"]/text()

I want to apply a condition on subcategory field and retrieve only document id which satisfy the condition mentioned.

{
"documents" : [
{
"documentId" : "FO85L_rlLqZbYIKYznec2kazlBDVh7zcvQeJ9ocxYPLlqd_LRYIHTqPg6q8",
"formName" : "Entente relative au prêt personnel CIBC",
"ingestionDate" : "2017-02-03",
"fileSize" : 205820,
"note" : "Different",
"mimeType" : "application/pdf",
"products" : [
{
"accountNumber" : "0007508061",
"transitNumber" : "00153",
"closedDate" : null,
"category" : "LENDING",
"subcategory" : "Loans"
}
]
},
{

    {
        "documentId" : "nVr94RcSPG7b03E6b-7SvK9HbIyg3Vr53nAqmKipEtR2j87DzHi3bjosEK7r",
        "formName" : "Demande de fermeture de compte pour consolidation de dettes",
        "ingestionDate" : "2017-02-03",
        "fileSize" : 88552,
        "note" : "Demande de fermeture de compte pour consolidation de dettes",
        "mimeType" : "application/pdf",
        "products" : [
            {
                "accountNumber" : "6244831",
                "transitNumber" : "00153",
                "closedDate" : null,
                "category" : "LENDING",
                "subcategory" : "PLC"
            }
        ]
    },
    {

        ]
    }
]

}