Document and Entity Information Document	3 Months Ended
	Mar. 31, 2015	Apr. 29, 2015
Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	MANT
Entity Registrant Name	MANTECH INTERNATIONAL CORP
Entity Central Index Key	0000892537
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Class A common stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		24,331,289
Class B common stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		13,192,845