Unfortunately IDM is not available for Ubuntu/Linux but there are many utilities are available which can give you fastest speed like wget and Axel are powerful download utilities.
to install it
sudo apt-get install wget axel
you may get confused how to use them in easy way. I have a nice technique which I usually do.
Type in terminal
Wget -c '<link>'.
Here link can be retrieved from firefox's download window .Begin Downloading any file from firefox . It will appear in firefox download box. Pause the download process. Right click on downloading file. Choose "Copy Link location"
Paste it in terminal in place of link. Here note that you should not missed single quote. If you want to stop then press CTRL+C best thing is that your download would never be corrupted and you can resume it by pressing Up key and enter( command again).