The default Referring Domain report in SiteCatalyst should just be named Referring Root Domain because a full referring domain would be plus.google.com not google.com. You can see full referrer data in the referrers report, but that requires a lot of manual effort to comb through.
Processing Rule that will give you Full Referring Domain:
![Referring Domain - Processing Rule.png Referring Domain - Processing Rule.png](https://forums.adobe.com/api/core/v3/images/1261808?a=1500596923966)