The 2015 US GAAP Taxonomy was developed by the Financial Accounting Financial Board (FASB) and has been accepted and supported by the SEC. It can be downloaded in its entirety from the links at the bottom of this page, along with other resources for implementation and use.
Namespace (all elements): http://fasb.org/us-gaap/2015
Recommended Namespace Prefix: us-gaap
Core schema and standard labels: http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-std-2015-01-31.xsd