Before launching into a detailed business plan, make sure you've considered all the key angles captured on the Lean Canvas (Ash Maurya) - http://leanstack.com/.

You might also care to check out the original business model canvas that inspired it - http://www.businessmodelgeneration.com/canvas/bmc.

Between them, you'll have at least nine of the critical aspects covered. Once you've done that you should consider whether you really need anything more than a focused slide-deck providing the next level of detail.

Ultimately you need to be clear on who is going to read your plan? and why? - then tailor it for their needs and the outcome you want.