Offline means offline. NO CLOUD! Get it on a hard or thumb drive, burn it to DVD, copy to floppies, or print it. Whatever you gotta do to get it off the internet.
I've been taking a screen shot of my bank accounts every three days or so. It's not a bad idea. Also download your statements offline.
If you have a Twitter account, there is a way to download your entire history. Do it monthly. On desktop in the left nav go to More --> Settings & privacy --> Account --> Your Twitter data. You'll get an email link to download.
