That's right but you negotiate a price and USAA cuts the check. Not cash but as with any purchase, you are paying the dealer for a car purchase. ED is no different...
I cannot say for sure as the OP would have to speak w/ USAA but ED is not unusual and USAA insures military members overseas so they are used to that aspect as well. Ultimately the OP needs to call USAA for an answer...
2011 Space Grey E90 M3, DCT, Comp. Pkg.
1997 Z3 2.8, Artic Silver, Tanin Red interior, MT
1974 2002tii, Inka, 5 sp manual
BMWCCA # 327475