It ended early:
DOUBLE REWARDS EVENT:
(DECEMBER 12, 2017 – JANUARY 1, 2018: BEGINS AND ENDS AT 4PM PST/12AM GMT)
Those are the details from the events page http://www.swtor.com/info/in-game-events . Normally I wouldn't complain but this is my first day off in months and I had lots of leveling planned out. Come on Bioware please fix this.