How to convert string to date format

I have string format data like below

Dec 26, 2014, 09:56 ET
Dec 31, 2014, 21:30 ET
Dec 30, 2014, 13:36 ET

And i want output in the below date format

26-12-2014 09:56:00
31-12-2014 21:30:00
30-12-2014 13:36:00

I have tried with the below code but it is giving different values. Correct me which syntax i can apply to convert string to date

str2date(input,"MMM dd, YYYY, HH:mm 'ET'")