In the US the airline that hires you provides the training. The idea of "line training" does not exist, except for Gulfstream and their BE-1900s if they are still in business. You will complete your ground school and sim training and for 10 to 25 hours, depending on the type of airplane and the kind of training you received, you will fly with a company check airman. The check airman will help you transition from the 'round and 'round the pattern with an emergency every 5 minutes in the sim to flying the plane like a normal pilot. In FAA land this used to be called Initial Operating Experience and is now just call Operating Experience or OE, since you do it after Initial training and Transition training and Upgrade training. Once the OE is completed in a week or so the pilot is released to the line and is just just another pilot. There are "High Mins" restrictions on new Captains for their first 100 hours and companies may place x-wind restrictions on low time pilots.