AC adapters and floating power supplies

Hi, thought I'd check in real quick to see if anyone knew the answer to this. If I buy a 15V AC adapter from the store, will it constitute a floating power supply or no? Is there a way to tell before purchasing? Basically, I'm trying to generate +/- 15V for op-amp circuitry and it seemed to me that an easy way to do this would be to get two floating 15 V supplies.