Detail isn't always necessary. Especially in a writing setting, sometimes a mention of past events is enough. Law of conservation of detail, don't waste any effort on writing details of events that don't matter to the story. Is it important to know that Mr. X got freaky with Ms. Y? Maybe. Is it important to know the length of involved male genetalia, approximate force of thrusts, the exact thoughts going on at a given point in time during the event? Not really. Mention the former, don't waste text on the irrelevancies.