The element of a contract that concerns the exchange of benefits and detriment is?

Badly worded question. Consideration is usually monetary, but can be other. It is not usually described in a benefit/detriment context, however. The consideration is a benefit to the party receiving it. The party furnishing the consideration receives a benefit, as well: the goods, the benefit of the promised performance or other subject matter of the contract. A burden verses benefit ysis is sometimes used by appellate courts in the context of tort jurisprudence. The answer you have in mind is undoubtedly consideration but, again, it is not usually described as an "exchange of benefits and detriment", at least not under a more contemporary "bargain theory"-oriented view of consideration.