Perhaps simplistically, I think you need:
1)
An explicit policy explaining what decisions should be handled at what levels. For this, of course, you need to be able to segment your decisions. This can be done by process, dollars, area, etc.
2)
To instruct managers to refrain from making the decisions that should be made by their subordinates, even when, for the managers themselves, making the decision is the easy solution in any one case.
3)
Encourage and reward initiative. You must never look at any one "at bat". Base your feedback on batting averages.