Document and Entity Information - shares	3 Months Ended
	Jun. 30, 2019	Jul. 26, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Trading Symbol	VSAT
Entity Registrant Name	VIASAT INC
Entity Central Index Key	0000797721
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--03-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		61,296,789
Entity File Number	000-21767
Entity Tax Identification Number	330174996
Entity Incorporation State Country Code	Delaware
Entity Address, Address Line One	6155 El Camino Real
Entity Address, City or Town	Carlsbad
Entity Address, Postal Zip Code	92009
Entity Address, State or Province	California
City Area Code	(760)
Local Phone Number	476-2200