Right now I'm opening word, inserting a file, saving, and exiting word. How do I close the file before exiting out of word?

Here's what I have already. Variables are populated earlier in the script...
code:
$WordDoc = CreateObject('Word.Application')
$AddTemplate = $WordDoc.Documents.Add(E:\Invoices\Templates\$Template.doc)
$WordDoc.Selection.InsertFile($DirectoryPath\$FileToFormat)
$FormattedDoc = SubStr($FileToFormat,1,Len($FileToFormat) -4)
$SaveWordDoc = $WordDoc.ActiveDocument.SaveAs("$SavePath\$FormattedDoc.doc",0)
$WordDoc.Quit(0)