You should have received a Form 1099-R for your distribution from Northern Trust. After you enter(ed) the 1099-R, there is a page that asks "What Did You Do With The Money From [Retirement Plan]"? See Screen Shot below.
Be sure you indicate that you "rolled over all of this money to an IRA or other retirement account (or returned it to the same account)." See Screen Shot #2 below.
Answering these questions correctly will result in your distribution showing up as non-taxable.
