There was supposed to be a showdown between Cassadee Pope of "The Voice" and Candice Glover of Idol with both releasing albums on October 8. But Candice has fled to February, making her one of the few (if any) Idol winners to not release an album in time for the Christmas season.
Cassadee would have won this battle anyway because although Candice is a more talented vocalist, Cassadee is simply more popular and was out touring with Rascal Flatts over the summer.
Hits Daily Double is reporting that Cassadee's album has sold around 45K in its first week. That is the best showing by far of any contestant from The Voice, but it is unlikely the album will ever reach gold. However, Cassadee has a single from the album, "Wasting All These Tears," which has sold over 400K, which is huge for a contestant from The Voice.
Phillip Phillips' debut album "The World from the Side of the Moon" has culminated it's slow, steady climb to platinum status by selling its millionth copy this month (September).
Off the top of my head, other Idols who have had platinum albums include Kelly Clarkson, Clay Aiken, Ruben Studdard, Fantasia, Carrie Underwood, Taylor Hicks, Chris Daughtry, Jordin Sparks, David Cook, Adam Lambert and Scotty McCreery.
By platinum, I mean at least one million sold worldwide. So for Seasons 1 through 11, only Season 9 failed to produce a platinum album.