Risk/Return Detail Data - VIPSectorFunds-InitialComboPRO	Apr. 30, 2025 USD ($)
Risk/Return:
Registrant Name	Variable Insurance Products Fund IV
VIPSectorFunds-InitialComboPRO | VIP Communication Services Portfolio
Risk/Return:
Risk/Return [Heading]	Fund Summary Fund /Class: VIP Communication Services Portfolio /Initial Class
Objective [Heading]	Investment Objective
Objective, Primary [Text Block]	VIP Communication Services Portfolio seeks capital appreciation.
Expense [Heading]	Fee Table
Expense Narrative [Text Block]	The following table describes the fees and expenses that may be incurred, directly or indirectly, when you, as a variable product owner, buy, hold, and sell interests in a separate account that invests in shares of the fund. The table does not include any fees or other expenses of any variable annuity or variable life insurance product; if it did, overall fees and expenses would be higher.
Shareholder Fees Caption [Text]	Fees
(fees paid directly from your investment)
Operating Expenses Caption [Text]	Annual Operating Expenses
Portfolio Turnover [Heading]	Portfolio Turnover
Portfolio Turnover [Text Block]	The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 73 % of the average value of its portfolio.
Portfolio Turnover, Rate	73.00%
Expenses Restated to Reflect Current [Text]	Adjusted to reflect current fees.
Expense Example Narrative [Text Block]	This example helps compare the cost of investing in the fund with the cost of investing in other funds. Let's say, hypothetically, that the annual return for shares of the fund is 5% and that the fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. This example does not include any fees or other expenses of any variable annuity or variable life insurance product; if it did, overall expenses would be higher. For every $10,000 invested, here's how much you, as a variable product owner, would pay in total expenses if all interests in a separate account that invests in shares of the fund were redeemed at the end of each time period indicated:
Strategy [Heading]	Principal Investment Strategies
Strategy Narrative [Text Block]	Normally investing primarily in common stocks. Normally investing at least 80% of assets in securities of companies principally engaged in the development, production, or distribution of communication services. These companies may include, for example, interactive media and services including search engines, social media and networking platforms; companies that produce and sell entertainment and media such as movies, TV, cable, radio, internet and satellite companies; interactive gaming and home entertainment products and services; advertising; publishing and public relations companies; operators of fixed-line telecommunications networks and companies; providers of cellular or wireless communications services and equipment; and providers of communications and high-density data transmission services and equipment. For purposes of the fund's policy to normally invest at least 80% of its assets in securities of companies principally engaged in the business activity or activities identified for the fund, Fidelity may consider a company to be principally engaged in the designated business activity or activities based on: (i) the level of a company's assets, income, sales, or profits that are committed to, derived from, or related to the designated business activity or activities, or (ii) whether a third party has given the company an industry or sector classification consistent with the designated business activity or activities. Whether a company is principally engaged in the designated business activity or activities can be determined under any of these factors. Effective December 11, 2025, derivative instruments that provide investment exposure to the investments above or exposure to one or more market risk factors associated with such investments are included in the fund's 80% policy, consistent with the fund's investment policies and limitations with respect to investments in derivatives. Investing in domestic and foreign issuers. Using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments.
Strategy Portfolio Concentration [Text]	Normally investing at least 80% of assets in securities of companies principally engaged in the development, production, or distribution of communication services.
Risk [Heading]	Principal Investment Risks
Bar Chart and Performance Table [Heading]	Performance
Performance Narrative [Text Block]	The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and an additional index over various periods of time. The additional index has characteristics relevant to the fund's investment strategies. Index descriptions appear in the "Additional Index Information" section of the prospectus. Past performance is not an indication of future performance. Prior to December 1, 2018, the fund was named VIP Telecommunications Portfolio, and the fund operated under certain different investment policies and compared its performance to a different additional index. The fund's historical performance may not represent its current investment policies. Returns for shares of the fund do not include the effect of any sales charges or other expenses of any variable annuity or variable life insurance product; if they did, returns for shares of the fund would be lower.
Performance Information Illustrates Variability of Returns [Text]	The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and an additional index over various periods of time.
Performance Past Does Not Indicate Future [Text]	Past performance is not an indication of future performance.
Bar Chart [Heading]	Year-by-Year Returns
Bar Chart Does Not Reflect Sales Loads [Text]	Returns for shares of the fund do not include the effect of any sales charges or other expenses of any variable annuity or variable life insurance product; if they did, returns for shares of the fund would be lower.
Highest Quarterly Return, Label	Highest Quarter Return
Highest Quarterly Return, Date	Jun. 30, 2020
Highest Quarterly Return	26.55%
Lowest Quarterly Return, Label	Lowest Quarter Return
Lowest Quarterly Return, Date	Jun. 30, 2022
Lowest Quarterly Return	(22.15%)
Performance Table Heading	Average Annual Returns
VIPSectorFunds-InitialComboPRO | VIP Communication Services Portfolio | VIP Communication Services Portfolio - Initial Class
Risk/Return:
Management fee	0.58%	[1]
Distribution and/or Service (12b-1) fees	none
Other expenses	0.03%	[1]
Total annual operating expenses	0.61%
1 year	$ 62
3 years	195
5 years	340
10 years	$ 762
2015	2.34%
2016	22.81%
2017	2.05%
2018	(5.36%)
2019	32.98%
2020	35.60%
2021	15.65%
2022	(38.14%)
2023	57.39%
2024	34.04%
VIPSectorFunds-InitialComboPRO | VIP Communication Services Portfolio | Return Before Taxes | VIP Communication Services Portfolio - Initial Class
Risk/Return:
Label	Initial Class
Past 1 year	34.04%
Past 5 years	15.40%
Past 10 years	12.69%
VIPSectorFunds-InitialComboPRO | VIP Communication Services Portfolio | SP001
Risk/Return:
Label	S&P 500® Index
Past 1 year	25.02%
Past 5 years	14.53%
Past 10 years	13.10%
VIPSectorFunds-InitialComboPRO | VIP Communication Services Portfolio | F1526
Risk/Return:
Label	MSCI U.S. IMI Communication Services 25-50 Index
Past 1 year	33.06%
Past 5 years	11.57%
Past 10 years	9.55%

[1] A Adjusted to reflect current fees.