How do I account for payments made on behalf of another company?

Scenario:

Company A buys and sells property. Company B (my company) pays for expenses on behalf of Company A, but Company A does not pay Company B back until after it has sold it's property or develops the land that generates income (both of which can take months or even years to become fully realized). Company B either pays expenses on Company A's behalf directly (purchasing of materials, plumbing, etc.) or hires a third party entity in which Company B pays for.

This may seem like a general question, but how do I account for the expenses incurred by Company B on behalf of Company A (for both direct expenses paid by Company B and expenses paid to a third party entity)? Do I treat this as a reimbursable expense or a normal expense for Company B?

Also, how would I treat payments made by Company A to Company B when they eventually pay Company B back? These payments would net everything out, but it could be years down the line when Company A pays back Company B.

I would also like to see a report that shows all of the expenses paid by Company B on behalf of Company A.