Read The Phoenix Project!
This is exactly why companies need oversight, you need to badger colleagues to document and record, get organised people. I hate this idea that just because you're asked to document your work and record things, that you're getting the boot next week. No one is trying to steal your job! We need the knowledge so that we can keep you and your job. You vanish on holiday for 2 weeks and no one knows what you do you put the whole company a risk and everyone's job.
Get your head out of your arse and get stuff written down, and sensitive stuff stored securely, even if it's just a print out given to the IT manager or even get Finance to put it in their safe. On the other hand the more you hoard knowledge, the more complaints HR may receive about you and then you're considered a risk for not complying with regs, this means they may find some way to demote or remove you for not complying.
You may not be going full on "DevOps" but the TPJ has a lot of sensible ideas about ensuring work is documented, critical people who cause bottlenecks are utilised correctly and knowledge is recorded so others can step in when needed to keep companies in crisis moving along.