IDK - "I don't know" - leadership. Probably not something we'd put on our business cards or in our resumes.
However, I would propose that as leaders we do not need to know everything. In fact, it might be better for everyone if we don't know everything, so that we'll rely on our team members and experts for details and information. If others are well-versed in the details and specifics, then we can focus on the decisions that need to be made with that information. We can focus on what to do with the information.
But the confidence and courage to say "I don't know" is tough to gain. Like everything else it takes practice. And it takes confidence in what you CAN do. As a leader, your role should be knowing who has the information, what factors need to be considered in using that information and how the decision can best me made for the good of the organization. That means you have a robust network, you know the budget and resources available, who must be involved in the final decision and the goals and direction of the organization.
Your role as leader isn't to understand every detail; it's to know who has those details. And that's difficult if you've been the expert for a long time and if others are pushing you to continue to be the expert. Once you demonstrate relying on others' expertise to facilitate smart decisions, your team and co-workers will appreciate your new expertise: that of a leader.
A quick example to illustrate this is my role as President of our Homeowner's Association. In our rural location, road work is an important, and sometimes contentious, topic, since owners have different standards and roadwork can be expensive. Some of the owners have roadwork expertise from past jobs and volunteered to form a road committee which I highly supported. I have no desire, nor the background, to become an expert in how to build a road. I did read their road report with details of the best way to build road so I would have a general understanding. We've established that their role as an "expert" committee is to provide the details and the proposals and my role is to understand the concerns and questions, as well as the budget and decision process we need to approve any work.
IDK can be a good thing for leaders, if those leaders have confidence in their teams and in their own abilities to manage and use the information. To build that confidence, start with an assessment of team members to understand their areas of expertise. Then IDK might become "We know."