I am planning to call my parents to vist us is the US. I am on H1 and am sponsoring their visit.

What are the docs. needed to apply for the visa? I already have the employment verification letter from my company and a letter from my wife's physician stating that she is expecting a baby. Do I need to send my bank statement and affidavit of support etc? My dad was asking me if he has to show his bank statement even if I send mine.What other documents are required to support their visa application? Please share if you have gone through this.I just want to make sure that I have all the documents.

Thanks in advance