We suggest that you arrive at the airport at least 3 hours prior to flight departure for international travel, 3.5 hours if you have a rental car to return. For domestic travel, arrive approximately 2 hours before your scheduled flight departure. For your peace of mind and to avoid problems you should monitor conditions such as traffic, weather, or anything that may affect your check-in (such as traveling during a holiday).
Airlines can and will charge fees if they are able to re-schedule missed flights. Be aware that if you miss your outbound flight the airline will consider you a 'NO SHOW' and cancel all subsequent flights.