This type of insurance typically covers both bodily injury and property damage. Depending on the policy, it can also cover work loss or other costs associated with accidents.
While an umbrella policy extends your car insurance policy’s limits, it is secondary coverage. If you don’t have uninsured motorist coverage on either your primary policy or your umbrella policy, you will not have any coverage if you get in an accident with an uninsured driver. You’ll be responsible for all costs related to the accident.
You can never have too much coverage with car insurance. If you can afford to add it to your policy, you should consider doing so.