The document number on your New York State drivers license is a combination of 8-10 letters and numbers. It is found on the back of your driver's license. You will enter the letters or numbers as requested in TurboTax.
You can find the Document Number (an 8 or 10-character combination of numbers and letters) on the back of your NYS Drivers License in the first line of text after IDUSA. You will not enter IDUSA as part of your document number. You will enter the numbers or characters after IDUSA.
You can see examples at the New York Department of Motor Vehicles website.
Your NYS Drivers License will look something like this:
Click here for "Where do I find my document number so that I can e-file my New York return?"