Depends on which state and city you would like to buy, and lenders take into consideration whether you have a valid SSN for residency or any temporary. In California the norm for a down payment under FHA loans is 3.5%, conventional loans range from 4%+, although the norms will change next year 2017. If you have a temporary visa you may be able to qualify for a loan but a 30% down payment will be requested, along with higher than normal fees for the transaction, such as closing costs. If you plan to buy cash you won't need anything except for the full cash amount of purchase price on any property you would desire to buy.
If interested in Southern California area, feel free to contact me with any questions you may have through my profile.
Sonnocco Real Estate Group