Why Is My Maven Index So Big?

D:\data\user\.IntelliJIdea14\system\Maven is over 10GB in size!

There are 4 directories under D:\data\user\.IntelliJIdea14\system\Mave\Indices
Index0
Index1
Index2
Index3

Index2 and Index3 are 5GB each.

Are these copies or all part of the same index?

My maven settings.xml points to a corporate nexus

    <profiles>
        <profile>
            <id>mirror-profile</id>
            <activation>
                <activeByDefault>true</activeByDefault>
            </activation>
            <repositories>
                <repository>
                    <id>central</id>
                    <url>http://nexus.company.com/content/groups/common</url>
                    <releases>
                        <enabled>true</enabled>
                    </releases>
                    <snapshots>
                        <enabled>true</enabled>
                    </snapshots>
                </repository>
            </repositories>

Since this is a mirror of central is IDEA effectively indexing ALL maven jars in the world?