How do the commercially successful bands make their music? Do they all have collaboration from other musicians and help writing their songs?

I was listening to Paramore the other day and I just started wondering. Do bands who are very commercially successful like Paramore for example or just any band that makes it big like that have help writing their music or is it really just them coming up with everything together in a studio?

I mean I can imagine someone comes up with a riff or drum beat and they can go from there but all the fills and rhythms and patterns and all the intricacies in the song... I mean do they not have help from outside the band putting it all together? I'd imagine it's almost like a movie where they show all the credits at the end. Are there outside musicians helping bands piece together their songs or is it usually just the band themselves doing it all?