In 2014, Starbucks made headlines when it partnered with Arizona State University to offer its employees tuition reimbursement for its online courses, allowing them to finish their college degrees. Walmart, too, added nearly free college tuition as an employee perk, and a lot of companies offer at least some help to workers looking to further their educations.On Tuesday, Discover Financial Services (NYSE: DFS) became the latest company to go all in on offering employees a way to get their degrees for free.