I also used USAA non-owners insurance during the period I did not own a car. It was pretty inexpensive ($10/mo IIRC).
I took the insurance primarily to protect friends and family
who let me drive their cars during that period, and also provide personal liability insurance when driving other vehicles.
Also I don't believe that insurance would have done me any good in Europe
. In the few times I rented a car in Portugal
I took the full insurance offered by the rental company.
In order to get insurance from USAA you used to have to be an active duty member
of the US Armed Forces or honorable discharged/retired from service
. I think the member
ship rules may not be so restrictive anymore, so if you need the insurance, contact USAA and find out if you qualify. There have been several threads on this subject over the past few years, and the only company cited by posters offering this type of coverage that I remember was USAA.