Interviewed on campus which was 1:1. The interviewer was very nice and reassured me that there are no trick questions. Passed the first interview and was invited to a second round in Tulsa, OK. Drove to Tulsa and had two panel interviews where it was 2:1 and one hour each. They were all vice presidents and not very social guys. They did not smile at all. The interview questions were all read from a thick packet that they had and the questions would sometimes be very different from others which made it hard to draw on another experience. Overall, everyone I saw who worked there were much older.