What sort of detailed billing are you looking for? If you login to self serve, click on usage, then view details underneath messaging you can view the times, dates and number to which texts were sent and recieved.
If you want to received a detailed bill as an SMS, that's not possible. The only thing you can receive is that your bill is ready and the amount. If you want all the details, you'll need to go on self-serve as Allan suggested.