Tuition reimbursement is one of the major reasons I left my old company and signed with Lockheed 6 months ago. Lockheed's yearly reimbursement cap is based on the relevance of the degree. For engineers, Lockheed will cover up to $15K / calendar year for an engineering masters and up to $10K / calendar year for an MBA [I don't know if the caps differ for other employees, i.e. logistics or business personnel].
As long as the college is nationally accredited, you'll be fine. I say "nationally", because I believe there are some regional accreditations for community colleges that won't be accepted by LM. Online degrees through accredited colleges are accepted as well.
I'm about to start my engineering masters in a few weeks, and Lockheed is footing the bill. It's a great program! About half of younger engineers have taken or are currently taking advantage of it.