The employer's state ID number is supposed to be in box 15 on your W-2, after the two-letter state abbreviation. If it's not there, ask your employer what the number is. Or in most cases you can just enter the federal ID number without the hyphen.
If boxes 16 and 17 are blank or zero, you do not have to enter the employer's state ID. Just leave boxes 15, 16, and 17 empty in TurboTax. Don't enter anything in those boxes.
