1. A computer implemented method for detecting an original language of a translated document, comprising: retrieving, by a processor, the translated document; identifying by the processor, a language of the retrieved document; calculating, by the processor, a language model for the language of the retrieved document (LM(RD)); calculating, by the processor, a distinct vector as a difference between LM(RD) and a common language model for the language of the retrieved document (LMT(RD)); obtaining, by the processor, pair vectors for language model pairs associated with the language of the retrieved document; calculating, by the processor, a vector distance between the distinct vector and each pair vector; identifying, by the processor, a given pair vector within a threshold vector distance based on the calculated vector distance; identifying by the processor, the original language corresponding to the given pair vector as the original language of the retrieved document; and retrieving, by the processor, an original document in the original language of the retrieved document, wherein the original document was translated into the retrieved document.