You should take that number with a large grain of salt. Twenty years is more than likely the sum of the maximum sentences for each of the six charges.

Popehat has touched on this subject (how the media doesn't understand federal sentencing) from time to time.

https://popehat.com/2015/10/08/bad-reporting-on-matthew-keys...

https://popehat.com/2013/02/05/crime-whale-sushi-sentence-el...

https://popehat.com/2013/03/26/cloudy-with-a-chance-of-shitt...

https://popehat.com/2013/08/13/the-eric-holder-memorandum-on...