Every day, around 10,000 Americans age into Medicare. It's usually a health system's largest payer and it's only getting bigger.

At the same time, the federal government is trying to shift away from fee-for-service reimbursement for Medicare by piloting Medicare ACOs. ACOs have saved Medicare some money—but it's been tougher for providers, who can usually hit their quality goals but have had trouble sharing in the savings.

That's where Medicare Advantage comes in. Find out why the number of enrollees is expected to double by 2020 and why this could be a great opportunity to move in the right direction.