In terms of primary identification, most FI's will use state issued DL's, state ID cards, military ID cards or passports.
I have seen everything from credit cards to utility bills used as secondary forms of ID. Your CIP policy should stipulate what is acceptable and what isnt. The most important thing is to make sure you get the required information (Name, DOB, physical address and identification number).
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"100 victories in 100 battles isnt the most skillful. Subduing the other's military w/o battle is the most skillful." Sun-Tzu