Investments in Marketable Securities - Summary of Investments Classified As Available-For-Sale Securities (Parenthetical) (Detail)	Jun. 30, 2019 USD ($) Security	Dec. 31, 2018 USD ($) Security
Schedule of Available-for-sale Securities [Line Items]
Number of securities in unrealized gain position \| Security	136	3
Unrealized gains, aggregate	$ 261,000	$ 1,000
Number of securities in unrealized loss position \| Security	36	181
Unrealized losses, aggregate	$ 21,000	$ 416,000
Short-term investments - available for sale	273,513,000	276,741,000
Certificate of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments - available for sale	251,000
Short-term investments classified as available-for-sale, noncurrent	17,800,000
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments - available for sale		3,479,000
Short-term investments classified as available-for-sale, noncurrent	17,800,000	10,000,000
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized gains, aggregate	261,000	1,000
Unrealized losses, aggregate	21,000	416,000
Short-term investments - available for sale	273,262,000	273,262,000
Short-term investments classified as available-for-sale, noncurrent	17,800,000	10,000,000
Cash equivalents [Member] \| Certificate of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments - available for sale	0
Cash equivalents [Member] \| Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments - available for sale	0	0
Cash equivalents [Member] \| Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments - available for sale	0	0
Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized gains, individually	20,000	1,000
Unrealized gains, aggregate	261,000	1,000
Unrealized losses, individually	4,000	17,000
Unrealized losses, aggregate	$ 21,000	$ 416,000

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

+ Details

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

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109979856&loc=d3e26626-111562

+ Details

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

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in net income (available-for-sale), classified as noncurrent.

+ References

+ Details

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

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

+ Details

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

- Definition

Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

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

- Definition

Available for sale securities in unrealized gain positions qualitative disclosure number of positions greater than or equal to one year

+ References

No definition available.

+ Details

Name:	vktx_AvailableForSaleSecuritiesInUnrealizedGainPositionsQualitativeDisclosureNumberOfPositionsGreaterThanOrEqualToOneYear
Namespace Prefix:	vktx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt securities available for sale unrealized gain position accumulated gain.

+ References

No definition available.

+ Details

Name:	vktx_DebtSecuritiesAvailableForSaleUnrealizedGainPositionAccumulatedGain
Namespace Prefix:	vktx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_InvestmentTypeAxis=vktx_CertificateOfDepositMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_CommercialPaperMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CashAndCashEquivalentsAxis=us-gaap_CashEquivalentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: