Have time on your hands
Definition 1 of 1
Pro Tip 1/3Not busy
Used when someone has nothing urgent to do or no responsibilities at a given time. 
With the kids at camp, I suddenly have time on my hands.
Pro Tip 2/3Potential boredom
Can imply that the person might be bored because they don't have enough to do. 
I've finished all my projects and have time on my hands now, it's quite boring.
Pro Tip 3/3Subtle sarcasm
Sometimes used sarcastically, suggesting that someone is wasting time or lacks important things to do. 
He's counting the tiles in the kitchen? Looks like someone has too much time on their hands.