I've been scanning a lot of personal sensitive documents such as IDs, banking information, etc. in order to have backups available easily, and I have been wondering about the best way to securely store this information in the cloud.

The main requirements, in order of importance (in my mind at least) would be:

1. Security. Even if my cloud account is compromised the data itself should not be accessible without entering a second password.

2. Availability. It should be accessible from a computer but also a phone or any other (i)device.

3. Not limited to storing sensitive data. I should be able to have in the same service some other documents that I don't care about having "stolen" such as some random ebook or video that I wanted to backup. It means that it should have a high storage capacity available for a reasonable price.

Right now my best idea is to store a file encrypted via VeraCrypt on any generic cloud storage such as Dropbox, but it causes issues with availability.

Thanks for your suggestions!