None of the Idolmaster games made it overseas, but Namco Bandai might be localizing the Idolmaster: Shiny Festa series. Namco Bandai filed trademarks for The Idol Master and Shiny Festa in Europe.

These could be protective trademarks, but the Idolmaster series is seven years old. It would be odd for Namco Bandai to suddenly care about the Idolmaster games and a spinoff series all of the sudden.

If (and this is still an if) Namco Bandai wants to the Idolmaster to go international, Shiny Festa is their best bet since these are regular music/rhythm games, which have a larger audience than say an idol training simulation.