Good Will
About the data
Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.
Methodology
Companies should report their financial performance in their annual financial reports, and these are the best places to find this information.
For companies that file with the SEC, this information can be found within their "Form 10-K" filings. You can often find these documents by searching for "Company 10-k", or they can be found through the SEC's EDGAR search.