Originally Posted by
redchilly
^ This works great for paid one-way flights but not for flights booked with points or round trips where one leg became cheaper and the other became more expensive.
If you paid with points and have access to the account from where the points came, you can log in and then click on the "details" link on the right side of the web page (underneath "available points"). If you then view your Rewards Activity Details for the current year to date you will see all points expenditures (including the confirmation # for flights).