regex embedded {{ matching

I need to match the entire following statement:

{{CalendarCustom|year={{{year|{{#time:Y}}}}}|month=08|float=right}}

Basically whenever there is a { there needs to be a corresponding } with however many embedded { } are inside the original tag. So for example {{match}} or {{ma{{tch}}}} or {{m{{a{{t}}c}}h}}.

I have this right now:

(\{\{.+?(:?\}\}[^\{]+?\}\}))

This does not quite work.