A reason will be provided in the letter you will receive.
I've applied today and got declined. My wife applied right after I did and got approved. They emailed me the link to access the decision letter and see the reason they declined the application later today.
The length is 14 years or so, but I don't see this as a big issue considering an excellent credit score and good income. My wife has a bit better credit score (~840 vs. 810) and a slightly lower income.