How do I double all note values?

I was writing a score that was originally supposed to be written in 4/4 70bpm, but were deciding to bump the tempo to 4/4 140bpm. Is there a way for me to bump this tempo but have the values of the notes double.

(Ex: 16th notes at 70bpm turn into 8th notes at 140bpm.)

I'm trying to avoid having to go in and change the notes manually.