"Unparsable date" when trying to reformat a date String

Question

I want to reformat a given date String into a different format:

SimpleDateFormat simpleDateFormat = new SimpleDateFormat("EEEE, MMMM dd, yyyy 'at' KK:mm aa zzzz");   
SimpleDateFormat output = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date d = simpleDateFormat.parse(question.getOccur());
String formattedTime = output.format(d);

I'm getting this exception:

java.text.ParseException: Unparseable date: "Monday, December 7, 2015 at 12:05:13 PM Eastern Standard Time" (at offset 33)