Contingencies - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2016
Loss Contingencies [Line Items]
Loss contingency impact to net income attributable to Viasat, Inc. stockholders	$ 4.0
Loss contingency impact to net (loss) income attributable to noncontrolling interests, net of tax	$ 3.7
Loss contingency impact to basic net income per share attributable to Viasat, Inc. common stockholders	$ 0.08
Loss contingency impact to diluted net income per share attributable to Viasat, Inc. common stockholders	$ 0.07
Unfavorable Regulatory Action [Member]
Loss Contingencies [Line Items]
U.S. government contract-related reserves	$ 1.8	$ 1.6
Accrued Liabilities [Member]
Loss Contingencies [Line Items]
Accrued total loss contingency	8.8
Other Long Term Liabilities [Member]
Loss Contingencies [Line Items]
Accrued total loss contingency	$ 3.0
TrellisWare [Member]
Loss Contingencies [Line Items]
Minority interest ownership percentage by parent	52.00%		52.00%
Operating Segments [Member] | Government Systems [Member]
Loss Contingencies [Line Items]
Accrued total loss contingency	$ 11.8
Accrued loss contingency in uncharacterized damages	11.4
Accrued loss contingency in penalties	$ 0.4