Abstract: An automated banking machine (10) identifies and stores documents such as currency bills deposited by a user. The machine then selectively recovers such documents from storage areas and dispenses them to other users. The machine includes a sheet thickness detector (810) used for distinguishing single sheets from double sheets which pass through the machine. The thickness detector includes a radiation source (822). Radiation from the radiation source is directed by radiation guide (824) to a generally linear elongated radiation outlet (826) which extends transversely to the sheet path. A receiver (814) includes a radiation sensitive element (830) which is also transversely elongated relative to the sheet path. Sheets passing between the emitter and the receiver cause variations in the amount of radiation reaching the receiver. The transversely elongated surface of the sheet through which the transmission of radiation is sense enables accurately distinguishing single sheets from double sheets.