It is widely acknowledged that fixed expressions such as idioms have a processing advantage over non-idiomatic language. While many idioms are metaphoric, metonymic, or even literal, the effect of varying nonliteralness in their processing has not been much researched yet. Theoretical and empirical findings suggest that metonymies are easier to process than metaphors but it is unclear whether this applies to idioms. Two self-paced reading experiments test whether metonymic, metaphoric, or literal idioms have a greater processing advantage over non-idiomatic control sentences, and whether this is caused by varying nonliteralness. Both studies find that metonymic and literal idioms are read significantly faster than controls, while the advantage for metaphoric idioms is only tenuous. Only experiment 2 finds literal idioms to be read fastest of all. As compositionality of the idioms cannot account for these findings, some effect of nonliteralness is suggested, together with idiomaticity and the sentential context.