I'm creating a new category called Owners Deposit - Equity. What should the Detail Type be?

Hello there, loveseat.

The Detail Type you should select depends on your need. QuickBooks provide description for every detail type available in the lists so it can help you choose what's best for this category. See the sample screenshot below.

However, if you're unsure what detail type you would select, I recommend consulting your accountant so you'll able to choose the correct one. I've collected some articles for tips about handling accounts in COA:

• Learn about the chart of accounts in QuickBooks Online.
• Learn about account types and detail types in QuickBooks Online.

Please let me know if you have more concerns anything about QuickBooks, especially about adding accounts in the system. I'll be around to  help.