Do I need any other documents apart from ESTA?

Yes, you require your passport to travel to the US as well as your ESTA as the authorisation is centred around your passport number. This must be an electronic passport (ePassport) with a digital chip containing biometric information about the passport owner and that also has a machine readable zone on the biographic page. You can identify if you have a chip by checking if there is a small logo of a rectangle and a circle on the front of your passport, similar to this:
RFID chip in your passport logo
.
A machine readable passport is one that contains two lines of text on the bottom of the information page of your passport. This text contains symbols and letters that can be scanned by machines for information. The passport must also contain a digital photograph, i.e. one that is printed directly onto the data page.
Please be aware that if your passport is not machine readable and you’re a citizen from a Visa Waiver Program country, you would need to apply for a standard visa to visit the U.S.

Name changes and gender changes

If you have changed your legal name or gender, you will need to bring legal proof of any identity change as well as proof showing you were the holder of the previous identity, if you have not changed your passport yet.
Once you land in the United States, you will also need to fill any required paperwork, such as customs declarations, which may be filled in at an Automated Passport Control (APC) kiosk when you land.
You will also need to provide border agents with information on your United States point of contact and where you will be staying in the U.S., along with the reasons for your journey to the U.S. (whether for business or pleasure), and the duration of your stay.
Documents that support your answers to such questions may also be useful, such as copy of return flight tickets (showing you will not be present for more than 90 days in the U.S., and that you are travelling with a commercial carrier), receipts and tickets for travel and accommodation, etc.