Applied through university career website. Was contacted by university relations for a phone interview within a week. Phone interview was approximately 40 minutes, consisted of open-ended questions such as "tell me about yourself and about what you do at school", and then more behavioral questions such as "tell me about a time when...". Interview was very casual and seemed to be geared towards informing me about the company and further steps in the interview process.
After about a week, received a request to attend final-round interview in San Antonio. I was flown in and attended a pre-interview dinner with candidates for various internship positions and employees from different parts of the company. The next morning, the other candidates and I were taken to the company's main campus for breakfast, a building tour, an individual interview, and finally a presentation on employee benefits.
The individual interview was a very casual and comfortable process. Each candidate was sent off to interview with 1 or 2 senior employees. To my surprise, this interview was exclusively behavioral in nature and was described as solely intended to determine the candidate's fit with the company culture, as the best of the best had already been selected through the resume drop.
While the position is open to people from various business or math backgrounds, it seems that the majority of the people who work in Risk Management-type positions at USAA are very analytical and technical people with PhDs or Master's Degrees in statistics or mathematics. This could potentially be very offputting for someone who comes from a less analytical background, especially while having to socialize for long periods of time with those employees during the in-person interview process.
Overall, the company seems to have a very welcoming and personable culture. The culture is, of course, also very military oriented and appears to carry a hierarchical system of rank and respect which is not found in other companies.