Very well, I'll link the actual article which goes into greater detail.
https://www.snopes.com/fact-check/dems-impeach-gop-presidents/
Here is the snippet:
Here’s a simplified version of this process:
1. Representative introduces articles of impeachment.
2. Committee investigates matter and votes to send articles to full House.
3. House votes to impeach and sends the case to the Senate.
4. Senate votes to convict and the president is removed from office.
The impeachment efforts against Reagan, Bush Jr., and Bush Sr. only reached the first step of this process. These efforts didn’t receive much support from the Democratic party as a whole, and they never made their way out of committee for a vote in front of the full House. When Rep. Henry B. Gonzalez, D-Texas, introduced articles of impeachment against Reagan in 1987, the Associated Press reported that the effort had “virtually no chance of being approved”
Because only 2 out of the 6 Presidents actually took a vote to the House, the Impeachment process never truly started with Reagan, Bush Sr. and Bush Jr.