Most companies that do home AND auto will offer it. The trick (not really a trick) is that the umbrella can ONLY be added after you maximize coverage on home and auto.
Check the bogleheads forum for discussions on insurance.
> the umbrella can ONLY be added after you maximize coverage on home and auto.
This isn't universally true - I have an umbrella policy with USAA. They require me to have a minimum of coverage on my home and auto to have the umbrella policy, but it's not the maximum they offer. It's a couple tiers down.
Of course, the price for the umbrella policy might depend on your home/auto coverage.
Chubb - you need to go through a broker and I should note i also have homeowners insurance that has some liability coverage which I suspect also influences the umbrella rate - just find a broker that sells Chubb/aig/natgen/travelers that cater to high net worth individuals (you don’t need to be one! I had a renters insurance policy from Chubb right out of college) But those policies tend to be more customizable - and my experience is that they’re more inclined to pay claims
Check the bogleheads forum for discussions on insurance.