Yes, you should definitely subtract the insurance reimbursement amounts from what you spent.
The Casualty Loss Credit is to help you with what you had. to spend out-of-pocket to repair your home (not covered by insurance; including your deductible).
If you are claiming the loss in 2018, you can also claim the reimbursements in 2018, even though the loss occurred in 2017.
The good news is that you can claim the loss even if you don't Itemize.
Here's more info:
https://ttlc.intuit.com/replies/6469344
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