Shares Used In Computing Diluted Net (Loss) Income Per Share - Shares Used In Computing Diluted Net Income Per Share (Detail) - shares shares in Thousands	12 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Weighted average common shares outstanding used in calculating basic net (loss) income per share attributable to Viasat, Inc. common stockholders	58,438	52,318	48,464
Weighted average options to purchase common stock as determined by application of the treasury stock method		246	281
Weighted average restricted stock units to acquire common stock as determined by application of the treasury stock method		658	533
Weighted average potentially issuable shares in connection with certain terms of the ViaSat 401(k) Profit Sharing Plan and Employee Stock Purchase Plan		174	167
Weighted average shares used in computing diluted net (loss) income per share attributable to Viasat, Inc. common stockholders	58,438	53,396	49,445

No definition available.

Name:	us-gaap_EarningsPerShareAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 28A
-URI http://asc.fasb.org/extlink&oid=96947427&loc=d3e1500-109256

+ Details

Name:	us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=96947427&loc=d3e1505-109256

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

+ Details

Name:	us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=96947427&loc=d3e1448-109256

+ Details

Name:	us-gaap_WeightedAverageNumberOfSharesOutstandingBasic
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Potentially issuable shares in connection with certain terms of the amended ViaSat 401 (k) profit sharing plan and are included in the computation of diluted Earnings Per Share and shares issued per employee stock purchase plan and included in the computation of diluted Earnings Per Share.

+ References

No definition available.

+ Details

Name:	vsat_IncrementalCommonSharesAttributableToPotentiallyIssuablePerEmployeeProfitSharingPlanAndToStockIssuedPerEmployeeStockPurchasePlan
Namespace Prefix:	vsat_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate awards of nonvested shares to be issued to employees under a share-based compensation arrangement are considered restricted unit awards for purposes of computing diluted earnings per share. Such share-based awards shall be considered to be outstanding as of the grant date for purposes of computing diluted earnings per share even though their release may be contingent upon vesting. Those share-based awards are included in the diluted Earnings Per Share (EPS) computation even if the employees may not receive (or be able to sell) the stock until some future date. Accordingly, all shares to be issued shall be included in computing diluted EPS if the effect is dilutive. The dilutive effect of share-based compensation arrangements shall be computed using the treasury stock method. If the equity share options or other equity instruments are outstanding for only part of a period, the shares issuable shall be weighted to reflect the portion of the period during which the equity instruments were outstanding.

+ References

No definition available.

+ Details

Name:	vsat_IncrementalCommonSharesAttributableToRestrictedStockUnitsToAcquireCommonStock
Namespace Prefix:	vsat_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration