“Insolvency” exists:
1. When the insurer fails to meet its obligations as they mature;
2. When a stock insurer’s assets are less than the sum of its liabilities and its paid-in capital stock account;
3. When a mutual insurer’s assets are less than the sum of its liabilities and the minimum basic surplus required to be maintained by the insurer under this Code for authority to transact the kinds of insurance transacted; or
4. As otherwise expressly provided in this Code.