On Windows Server 2012 R2 with Update(which is compatible with Windows 8.1 Update 1), I copied a character U+20BB7 and pasted it on IDLE.  After that, IDLE suddenly exited with no messages, notices, or errors.

  Then, I tried to input some non-BMP charactors by the Google Japanese IME other than 𠮷 such as U+1F444, U+1F468 and found that the IDLE exited as the same way.

  I suppose that these phenomena could be due to a failure when treating surrogate pairs in input or pasted strings.

P.S.
  𠮷 is explained as U+20BB7 in UCS-4.  And the characters that is explaind as U+1F444(👄) and U+1F468(👨) are both what are said emojis(explains the mouth and man)

This looks as a duplicate of issue13153.

If you start IDLE from the console with 'python -m idlelib' you should see a TclError message when pasting.  This is a known limitation of tcl/tk.  Printing gives a traceback in IDLE's shell.
>>> print('\U00020BB7')
Traceback (most recent call last):
  File "<pyshell#26>", line 1, in <module>
    print('\U00020BB7')
  File "C:\Programs\Python35\lib\idlelib\PyShell.py", line 1344, in write
    return self.shell.write(s, self.tags)
UnicodeEncodeError: 'UCS-2' codec can't encode character '\U00020bb7' in position 0: Non-BMP character not supported in Tk