Those in the pic aren't on idle. Idle always shows itself as a build selected. Those, if visibility is actually there, are simply cities that have no build selected at all.
OK, But why can the player choose to build idle? Why would the player ever want to build it?
Code:
<ProcessInfo>
<Type>PROCESS_IDLE</Type>
<Description>TXT_KEY_PROCESS_IDLE</Description>
<Strategy>TXT_KEY_PROCESS_IDLE_STRATEGY</Strategy>
<TechPrereq>NONE</TechPrereq>
<ProductionToCommerceModifiers>
<iProductionToCommerceModifier>0</iProductionToCommerceModifier>
<iProductionToCommerceModifier>0</iProductionToCommerceModifier>
<iProductionToCommerceModifier>0</iProductionToCommerceModifier>
</ProductionToCommerceModifiers>
<Button>Art/Interface/Buttons/Process/ProcessIdle.dds</Button>
</ProcessInfo>