$K(H)$ is maximal if $H$ is separable.

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Let $H$ a Hilbert Space, $B(H)=\{T:H\to H :T$ is linear and continuous$\}$, $K(H)=\{T\in B(H):T$ is compact$\}$.

I already know that $K(H)$ is a simple algebra, this is, the only closed ideals of $K(H)$ is itself and $\{0\}$ (even though $H$ don't need be separable). But how I check that if $H$ is separable then $K(H)$ is maximal in $B(H$)?

What I found here is that "is well-know statement", so where I can find a proof?