$18 trillion but it's not like the people of this country aren't already paying for health care, education, etc. I imagine many of us probably wouldn't pay any more with these proposals; our taxes might go up but we wouldn't have to pay for health care, etc., privately anymore. So, the benefit is that not only do more people have access to all these services, but we also wouldn't have to worry about losing them if we lose our job or have any other financial hardships.
I imagine a lot of the extra budget required would be made up for by increasing taxes on the wealthy, as well, which is fine because they don't pay much right now, especially compared to other countries.
Try to take some basic rights to people in Denmark, Sweden, Norway, Finland, Holland, Belgium etc. They would riot - hell a large majority of people in UK would riot if any serious attempts are made to privatize the NHS.
Sure you can have private health care in most of those countries but that's not exactly cheaper than having it all taken care by your taxes. I'd understand if there was long term proof that mass education, healthcare, security can be cheaper by being handled by private companies. Especially when companies don't really care about people who can't afford their product.