[intellij-idea] How to change line width in IntelliJ (from 120 character)

I was wondering how I can change the line length in IntelliJ.

Since I use a pretty high resolution, I get that line that shows 120 characters straight through the middle of the screen. Can I change it from 120 to, say, 250?

I didn't understand why my this didn't work but I found out that this setting is now also under the programming language itself at:

'Editor' | 'Code Style' | < your language > | 'Wrapping and Braces' | 'Right margin (columns)'

You can alter the "Right margin" attribute in the preferences, which can be found via

File | Settings | Project Settings | Code Style - General

Right Margin (columns) In this text box, specify the number of columns to be used to display pages in the editor.

Source: Jetbrains

IntelliJ IDEA 2018

File > Settings... > Editor > Code Style > Hard wrap at

IntelliJ IDEA 2016 & 2017

File > Settings... > Editor > Code Style > Right margin (columns):

It seems like Jetbrains made some renaming and moved settings around so the accepted answer is no longer 100% valid anymore.

Intellij 2018.3:

hard wrap - idea will automatically wrap the line as you type, this is not what the OP was asking for

visual guide - just a vertical line indicating a characters limit, default is 120

If you just want to change the visual guide from the default 120 to lets say 80 in my example:

Also you can change the color or the visual guide by clicking on the Foreground:

Lastly, you can also set the visual guide for all file types (unless specified) here:

It may be useful to notice that very good answers given above may not be enough. It is because of one more tick is required here:

Be aware that need to change both location:

File > Settings... > Editor > Code Style > "Hard Wrap at"

and

File > Settings... > Editor > Code Style > (your language) > Wrapping and Braces > Hard wrap at