Label	Element	Value
Prospectus [Line Items]	rr_ProspectusLineItems
Document Type	dei_DocumentType	497
Document Period End Date	dei_DocumentPeriodEndDate	Dec. 31, 2022
Entity Registrant Name	dei_EntityRegistrantName	John Hancock Variable Insurance Trust
Entity Central Index Key	dei_EntityCentralIndexKey	0000756913
Entity Inv Company Type	dei_EntityInvCompanyType	N-1A
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Jun. 29, 2023
Document Effective Date	dei_DocumentEffectiveDate	Jul. 01, 2023
(Capital Appreciation Value Trust)
Prospectus [Line Items]	rr_ProspectusLineItems
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, the fund invests primarily in common stocks of established U.S. companies that have above-average potential for capital growth. Common stocks typically constitute at least 50% of the fund’s total assets. The remaining assets are generally invested in other securities, including corporate and government debt (including mortgage- and asset-backed securities), bank loans (which represent an interest in amounts owed by a borrower to a syndicate of lenders), foreign securities, futures and options. The fund may invest up to 20% of its total assets in foreign securities. The fund’s common stocks generally fall into one of two categories: the larger category comprises long-term core holdings whose prices when purchased by the fund are considered low in terms of company assets, earnings, or other factors; the smaller category comprises opportunistic investments whose prices the subadvisor expects to rise in the short term but not necessarily over the long term. There are no limits on the market capitalization of the issuers of the stocks in which the fund invests. Since the subadvisor attempts to prevent losses as well as achieve gains, the subadvisor typically uses a value approach in selecting investments. The subadvisor’s in-house research team seeks to identify companies that seem undervalued by various measures, such as price/book value, and may be temporarily out of favor but are believed to have good prospects for capital appreciation. The subadvisor may establish relatively large positions in companies it finds particularly attractive. In addition, the subadvisor searches for risk/reward values among all types of securities. The portion of the fund invested in a particular type of security, such as common stocks, results largely from case-by-case investment decisions, and the size of the fund’s cash reserve may reflect the subadvisor’s ability to find companies that meet valuation criteria rather than its market outlook. Bonds and bank loans may be purchased to gain additional exposure to a company or for their income or other features; maturity and quality are not necessarily major considerations in determining whether to purchase a particular security. Direct investments in loans may be illiquid and holding a loan could expose the fund to the risks of being a direct lender. The fund’s investments in below-investment grade debt securities and loans are limited to 30% of total assets. The fund may also purchase other securities, including bank debt, loan participations and assignments and futures and options. The fund’s investments in options, if any, will be primarily in an effort to protect against downside risk or to generate additional income. The fund holds a certain portion of its assets in money market reserves, which can consist of shares of certain internal T. Rowe Price money market funds as well as U.S. dollar and foreign currency-denominated money market securities, including repurchase agreements, in the two highest rating categories, maturing in one year or less. The fund may invest up to 10% of its total assets in hybrid instruments. Hybrid instruments are a type of high-risk derivative which can combine the characteristics of securities, futures, currencies and options. Such securities may bear interest or pay dividends at below (or even relatively nominal) rates. In addition, the fund may invest up to 10% of its total assets in mortgage- and asset-backed securities. The fund may sell securities for a variety of reasons including to realize gains, limit losses or redeploy assets into more promising opportunities. In pursuing the fund’s investment objective, the subadvisor has the discretion to purchase some securities that do not meet its normal investment criteria, as described above, when it perceives an unusual opportunity for gain. These special situations might arise when the subadvisor believes a security could increase in value for a variety of reasons including a change in management, an extraordinary corporate event, a new product introduction or a favorable competitive development.

Label

Element

Value

rr_ProspectusLineItems

Document Type

dei_DocumentType

497

Document Period End Date

dei_DocumentPeriodEndDate

Dec. 31, 2022

Entity Registrant Name

dei_EntityRegistrantName

John Hancock Variable Insurance Trust

Entity Central Index Key

dei_EntityCentralIndexKey

0000756913

Entity Inv Company Type

dei_EntityInvCompanyType

N-1A

Amendment Flag

dei_AmendmentFlag

false

Document Creation Date

dei_DocumentCreationDate

Jun. 29, 2023

Document Effective Date

dei_DocumentEffectiveDate

Jul. 01, 2023

(Capital Appreciation Value Trust)

Prospectus [Line Items]

rr_ProspectusLineItems

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal market conditions, the fund invests primarily in common stocks of established U.S. companies that have above-average potential for capital growth. Common stocks typically constitute at least 50% of the fund’s total assets. The remaining assets are generally invested in other securities, including corporate and government debt (including mortgage- and asset-backed securities), bank loans (which represent an interest in amounts owed by a borrower to a syndicate of lenders), foreign securities, futures and options. The fund may invest up to 20% of its total assets in foreign securities.

The fund’s common stocks generally fall into one of two categories: the larger category comprises long-term core holdings whose prices when purchased by the fund are considered low in terms of company assets, earnings, or other factors; the smaller category comprises opportunistic investments whose prices the subadvisor expects to rise in the short term but not necessarily over the long term. There are no limits on the market capitalization of the issuers of the stocks in which the fund invests. Since the subadvisor attempts to prevent losses as well as achieve gains, the subadvisor typically uses a value approach in selecting investments. The subadvisor’s in-house research team seeks to identify companies that seem undervalued by various measures, such as price/book value, and may be temporarily out of favor but are believed to have good prospects for capital appreciation. The subadvisor may establish relatively large positions in companies it finds particularly attractive.

In addition, the subadvisor searches for risk/reward values among all types of securities. The portion of the fund invested in a particular type of security, such as common stocks, results largely from case-by-case investment decisions, and the size of the fund’s cash reserve may reflect the subadvisor’s ability to find companies that meet valuation criteria rather than its market outlook.

Bonds and bank loans may be purchased to gain additional exposure to a company or for their income or other features; maturity and quality are not necessarily major considerations in determining whether to purchase a particular security. Direct investments in loans may be illiquid and holding a loan could expose the fund to the risks of being a direct lender. The fund’s investments in below-investment grade debt securities and loans are limited to 30% of total assets. The fund may also purchase other securities, including bank debt, loan participations and assignments and futures and options. The fund’s investments in options, if any, will be primarily in an effort to protect against downside risk or to generate additional income.

The fund holds a certain portion of its assets in money market reserves, which can consist of shares of certain internal T. Rowe Price money market funds as well as U.S. dollar and foreign currency-denominated money market securities, including repurchase agreements, in the two highest rating categories, maturing in one year or less.

The fund may invest up to 10% of its total assets in hybrid instruments. Hybrid instruments are a type of high-risk derivative which can combine the characteristics of securities, futures, currencies and options. Such securities may bear interest or pay dividends at below (or even relatively nominal) rates. In addition, the fund may invest up to 10% of its total assets in mortgage- and asset-backed securities.

The fund may sell securities for a variety of reasons including to realize gains, limit losses or redeploy assets into more promising opportunities. In pursuing the fund’s investment objective, the subadvisor has the discretion to purchase some securities that do not meet its normal investment criteria, as described above, when it perceives an unusual opportunity for gain. These special situations might arise when the subadvisor believes a security could increase in value for a variety of reasons including a change in management, an extraordinary corporate event, a new product introduction or a favorable competitive development.