Dot The I's And Cross The T's Meaning

(idiomatic) To take care of every detail, even minor ones; To be meticulous or thorough.

Example:   Before taking the project to the CEO, let's make sure we dot the i's and cross the t's.
1858, United States Congress, Abridgment of the Debates of Congress, from 1789 to 1856, D. Appleton, page 387; from a January 1820 debate
  Pray, sir, what is the object of referring a bill to a committee —merely to dot the i's and cross the t's?