What type of translation you use in idiom translation?

When translating an idiom, one can chose two ways to do so:

1. Literally; if the idiom has a similar synonym in both meaning and form in the target language, simply use the equivalent in the other language.

2. Ideally; which means translating the idea of the idiom, if no similar idiom is present in the target language. 

I translate the idiom according the context