You can download the latest IDEA version from Passport if you have an active license and access to Passport, or contact your distributor for the latest version.
The install process automatically uninstalls your existing IDEA version and installs the latest IDEA software (including CaseWare IDEA License Manager, if applicable) on the machine that currently hosts the IDEA software. You will not have to re-register your license.
Download the IDEA 12.3 software
Run the Executable file IDEA_12.3_EN_Standard-ASCII.exe and unzip the installation package
to create folder IDEA_12.2_EN_Standard-ASCII
In the IDEA_12.3_EN_Standard-ASCII folder navigate to and double-click Setup.exe.
Installation Wizard begins. To start the installation process, click Next.

- License Agreement Screen. Read and accept the license agreement and then click Next.