At Disney Cruising Group, on the subject of passports, we defer to to the official Government Agency site links:
Do I need a passport for my cruise?
Passport: Difference between passport book and passport card (includes cost/prices)
To apply for a passport: https://travel.state.gov/content/passports/en/passports/applyinperson.html
Renew a passport: https://travel.state.gov/content/passports/en/passports/renew.html
Below is the official Disney Cruise Line page regarding Travel Documentation: