How do I get PyCharm to show method signatures and documentation in the Python/IPython console and the editor?

In pycharm you have ctrl-q (or ctrl-j on a mac) for a quick-doc of the function under the cursor.

Ctrl + P to show method signature (parameters) as a pop-up.

other shortcut keys for pycharm are all available here.

If you are looking for Mac shortcut it's Command + P (⌘+P), accepted answer's solution didn't work.