Denominate a table as Date table

Hi,

 I Have a  table with 14 millions records with dates in quarter level , fiscal year, fiscal month, etc ... Not sure if the project is setup to have a Date Hierarchy or if the system created that hierarchy. That would be my first question. 

 And later, once I know that, I would like to understand if would be better to extract the dates to a different table and ´designate this one as the Date table, or if it's okay to designate this 14 millions record table as the Date table? 

Thanks,