If you are a homeowner and/or you drive a car, umbrella liability insurance may be a good idea. This insurance provides protection beyond your basic liability coverage, and protects you against catastrophic financial losses if you are sued. If you think you need at least a million dollars of additional liability protection, consider an umbrella policy. Luckily this type of policy is not expensive, and can be usually be purchased from your existing carrier.
Generally, you can change your level of umbrella liability by contacting your insurer. You will have to fill out an additional application, and if the amount of coverage is non-standard, you will undergo additional underwriting. It's a good idea to ask yourself every time you renew your insurance whether your coverage limits fit your life right now and if you need to increase any of them.
Who should consider it? Those who have a net worth (outside of work sponsored retirement accounts) which exceeds their basic liability coverage, those who expect the value of their future assets to be high from income or inheritance, those with unincorporated businesses and those with multiple drivers in the family (especially teenagers!).
For more information, read this blog post by my colleague Scott Spann.