JetBrains is actually from Czech Republic, not Russia. Yes, they have offices in Moscow and SPB, but also in Munich and Boston - that does not make them German or US company either.
I think the owner decided to register the firm in Czech Republic because it is more western and also a country with Slavic language. As far as I know both the owner and majority of developers are from Russia.
You are right, I had a look into business register and names of owners like Sergey and Valentin are not exactly Czech names.
It's definitely among the best, but I believe Visual Studio is better.
Still, not enough to say Russia is the world leader in software development. That title still belongs to the US of A for now.
But Visual Studio wouldn't be the same without the great ReSharper :) By the way, Google's recent Android Studio - the best Android IDE, which pushed Eclipse aside - is a customized IntelliJ Idea as well (they made a deal).