1. A computer-implemented method comprising: storing, in memory, a plurality of classified data patterns for personal identifiers, the plurality of classified data patterns corresponding to variations of personal identifier formats, the personal identifiers including confidential information of a plurality of entities; identifying a text document to be searched; searching the text document for data expressed in a format that matches any of the plurality of classified data patterns corresponding to the variations of personal identifier formats; finding, in the text document, one or more personal identifier candidates matching any of the plurality of classified data patterns; and validating each of the personal identifier candidates using one or more personal identifier validators to provide accurate detection of the confidential information in the text document.