Stock-Based Compensation - (Stock Option) - Additional Information (Detail) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2020 USD ($) installment $ / shares	Mar. 31, 2019 USD ($) $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation option awards contractual term	10 years
Portion of initial stock options granted to employees that vests on employee's first anniversary	25.00%
Portion of initial stock options granted to employees that vests ratably over three years after completion of first year of service	75.00%
Number of vesting equal installments \| installment	36
Vesting period for subsequent stock options granted to directors	4 years
Options granted, weighted average fair value per share (in dollars per share) \| $ / shares	$ 5.73	$ 11.50
Proceeds from exercise of employee stock options	$ 479	$ 179
Service option awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses	$ 9,100
Unrecognized compensation expenses, weighted average period	1 year 6 months

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cost to be recognized for option under share-based payment arrangement.

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of cash inflow from exercise of option under share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=SL79508275-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromStockOptionsExercised
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of new hire stock option award that vests after one year of service.

+ References

No definition available.

+ Details

Name:	vnda_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfShareSubjectToOptionAwards
Namespace Prefix:	vnda_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of new hire stock option award that vests monthly after one year of service.

+ References

No definition available.

+ Details

Name:	vnda_ShareBasedCompensationArrangementByShareBasedPaymentAwardRemainingPercentageOfShareSubjectToOptionAwards
Namespace Prefix:	vnda_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Period which an employee and new director's right to exercise an annual option award is no longer contingent on satisfaction of either a service, market or a performance condition.

+ References

No definition available.

+ Details

Name:	vnda_ShareBasedCompensationArrangementbyShareBasedPaymentAnnualAwardVestingPeriodEmployeesandNewDirectors
Namespace Prefix:	vnda_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual term of stock option awards.

+ References

No definition available.

+ Details

Name:	vnda_ShareBasedCompensationOptionAwardsContractualTerm
Namespace Prefix:	vnda_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based Compensation Arrangement by Share-Based Payment Award, Options, Vesting Period, Number Of Equal Monthly Installments

+ References

No definition available.

+ Details

Name:	vnda_SharebasedCompensationArrangementbyShareBasedPaymentAwardOptionsVestingPeriodNumberOfEqualMonthlyInstallments
Namespace Prefix:	vnda_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AwardTypeAxis=vnda_ServiceOptionAwardsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: