Conditional Formatting - Numerical String Ending With Alphabetical Value?

I am working with a somewhat lengthy worksheet with over 60,000 records. oOne of the columns within the worksheet is the "Account Number" column, which typically consists of 14 numerical characters, but can sometimes have additional or fewer characters. I need to set up a conditional format to pick up any account number that ends in an alphabetical value, (e.g. a through z). The account number is located in column G.