dot the i's and cross the t's idiom
（尤指在完成某项工作时）一丝不苟，注重细节
to pay a great deal of attention to the details of something, especially when you are trying to complete a task
The negotiations are nearly finished, but we still have to dot the i's and cross the t's. 谈判即将结束，但是我们还是要做到一丝不苟。