If you are interested in creating a Provisional Utility Patent you can do it yourself for about $75.  It may be easier to just get an NDA, but some large companies will not consider an NDA and will only let you document your ideas this way for exceptions to non-competes and intellectual property agreements.  I understand in business you can trust no one.  But on the other hand companies have to allow for innovation and have a exception process for ideas they are not interested in or in a market they don’t compete in.

http://www.uspto.gov/ebc/efs/downloads/efsabx.htm