The principal directory of insurance companies is Best's Insurance Reports, which has domestic "Life-Health," "Property-Casualty" and "International" editions (see "A.M. Best"). In addition to the print volumes, company reports and news articles can be purchased on the A.M. Best Web site and through Lexis (COMPNY;AMBEST).
Another directory: Some insurance companies are profiled in the Mergent Bank and Finance Manual.
Also visit the company's Web site - most insurance companies post a lot of information - and the Web site of the insurance commissioner for the relevant state(s). The NAIC maintains a clickable map with links to each state's insurance commissioner Web site.
NAIC Filings: Most insurance companies make annual and quarterly filings with the National Association of Insurance Commissioners (NAIC). The NAIC puts the information into several databases (e.g., "assets," "claims paid," etc.) and provides this information to the public. Basic information is available free in the Company Search for Complaint and Financial Information; if you can provide the name of the company and a state where it does business, you can find the company's home state, the type of insurance it provides, the NAIC number, the number of closed complaints filed against the company, the dollar value of premiums written for each state plus the company's total premiums written, assets and liabilities, and possibly even get the company's Annual Statement. Complete annual and quarterly statements in PDF format can be downloaded from the NAIC's InsData site for a moderate charge.
Instructions for making NAIC filings are published in the NAIC's Annual and Quarterly Statement Instructions (available from the NAIC Store). For questions regarding filings, contact the NAIC's Insurance Products and Services Division at 816-783-8300.
Ratings: For ratings on the financial health of insurance companies see "Insurance Ratings."
SEC Filings: Many insurance companies are public and therefore make informative public filings with the SEC. For information on how to get SEC filings, see the Filings section of "Securities and Exchange Commission."