This semi-annual shareholder report contains important information about iShares Short-Term TIPS Bond Index Fund (the “Fund”) for the period of January 1, 2024 to June 30, 2024.

Shareholder Report Annual or Semi-Annual

semi-annual shareholder report

Additional Information [Text Block]

You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.

Additional Information Phone Number

(800) 441‑7762

Additional Information Website

blackrock.com/fundreports

Expenses [Text Block]

What were the Fund costs for the last six months?

(based on a hypothetical $10,000 investment)

Class name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
Institutional Shares	$6	0.11%

Expenses Paid, Amount

$ 6

Expense Ratio, Percent

0.11%

Performance Past Does Not Indicate Future [Text]

Past performance is not an indication of future results.

Average Annual Return [Table Text Block]

Average annual total returns
	6-Month Total Returns	1 Year	5 Years	Since Inception
Institutional Shares	2.34)%	5.29%	3.03)%	2.67%
ICE BofA US Broad Market Index	(0.47)%	2.71%	(0.23)%	1.11%
Bloomberg U.S. Treasury Inflation-Protected Securities (TIPS) 0-5 Years Index (Series-L)	2.26)%	5.37%	3.16)%	2.77%

Performance Inception Date

Feb. 16, 2016

No Deduction of Taxes [Text Block]

Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.

Updated Performance Information Location [Text Block]

Visit blackrock.com for more recent performance information.

Net Assets

$ 299,009,907

Holdings Count | Holding

Investment Company Portfolio Turnover

9.00%

Additional Fund Statistics [Text Block]

Key Fund statistics
Net Assets	$299,009,907%
Number of Portfolio Holdings	$28%
Portfolio Turnover Rate	$9%

Holdings [Text Block]

What did the Fund invest in?

(as of June 30, 2024)

Maturity allocation
Period	Percent of Total Investments^(a)
1-2 Years	23.0%
2-3 Years	23.6%
3-4 Years	27.0%
4-5 Years	26.4%

Five largest holdings
Security	Percent of Total Investments^(a)
U.S. Treasury Inflation-Indexed Notes, 2.38%, 10/15/28	5.6%
U.S. Treasury Inflation-Indexed Notes, 2.13%, 04/15/29	5.0%
U.S. Treasury Inflation-Indexed Notes, 0.38%, 07/15/25	4.9%
U.S. Treasury Inflation-Indexed Notes, 1.25%, 04/15/28	4.8%
U.S. Treasury Inflation-Indexed Notes, 1.63%, 10/15/27	4.8%

(a)	Excludes short-term securities.

Largest Holdings [Text Block]

Five largest holdings
Security	Percent of Total Investments^(a)
U.S. Treasury Inflation-Indexed Notes, 2.38%, 10/15/28	5.6%
U.S. Treasury Inflation-Indexed Notes, 2.13%, 04/15/29	5.0%
U.S. Treasury Inflation-Indexed Notes, 0.38%, 07/15/25	4.9%
U.S. Treasury Inflation-Indexed Notes, 1.25%, 04/15/28	4.8%
U.S. Treasury Inflation-Indexed Notes, 1.63%, 10/15/27	4.8%

(a)	Excludes short-term securities.

C000166148 [Member]

Shareholder Report [Line Items]

Fund Name

iShares Short-Term TIPS Bond Index Fund

Class Name

Investor A Shares

Trading Symbol

BAIPX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about iShares Short-Term TIPS Bond Index Fund (the “Fund”) for the period of January 1, 2024 to June 30, 2024.

Shareholder Report Annual or Semi-Annual

semi-annual shareholder report

Additional Information [Text Block]

You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.

Additional Information Phone Number

(800) 441‑7762.

Additional Information Website

blackrock.com/fundreports.

Expenses [Text Block]

What were the Fund costs for the last six months?

(based on a hypothetical $10,000 investment)

Class name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
Investor A Shares	$18	0.36%

Expenses Paid, Amount

$ 18

Expense Ratio, Percent

0.36%

Performance Past Does Not Indicate Future [Text]

Past performance is not an indication of future results.

Average Annual Return [Table Text Block]

Average annual total returns
	6-Month Total Returns	1 Year	5 Years	Since Inception
Investor A Shares	2.20)%	5.02%	2.76)%	2.40%
ICE BofA US Broad Market Index	(0.47)%	2.71%	(0.23)%	1.11%
Bloomberg U.S. Treasury Inflation-Protected Securities (TIPS) 0-5 Years Index (Series-L)	2.26)%	5.37%	3.16)%	2.77%

Performance Inception Date

Feb. 16, 2016

No Deduction of Taxes [Text Block]

Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.

Updated Performance Information Location [Text Block]

Visit blackrock.com for more recent performance information.

Net Assets

$ 299,009,907

Holdings Count | Holding

Investment Company Portfolio Turnover

9.00%

Additional Fund Statistics [Text Block]

Key Fund statistics
Net Assets	$299,009,907%
Number of Portfolio Holdings	$28%
Portfolio Turnover Rate	$9%

Holdings [Text Block]

What did the Fund invest in?

(as of June 30, 2024)

Maturity allocation
Period	Percent of Total Investments^(a)
1-2 Years	23.0%
2-3 Years	23.6%
3-4 Years	27.0%
4-5 Years	26.4%

Five largest holdings
Security	Percent of Total Investments^(a)
U.S. Treasury Inflation-Indexed Notes, 2.38%, 10/15/28	5.6%
U.S. Treasury Inflation-Indexed Notes, 2.13%, 04/15/29	5.0%
U.S. Treasury Inflation-Indexed Notes, 0.38%, 07/15/25	4.9%
U.S. Treasury Inflation-Indexed Notes, 1.25%, 04/15/28	4.8%
U.S. Treasury Inflation-Indexed Notes, 1.63%, 10/15/27	4.8%

(a)	Excludes short-term securities.

Largest Holdings [Text Block]

Five largest holdings
Security	Percent of Total Investments^(a)
U.S. Treasury Inflation-Indexed Notes, 2.38%, 10/15/28	5.6%
U.S. Treasury Inflation-Indexed Notes, 2.13%, 04/15/29	5.0%
U.S. Treasury Inflation-Indexed Notes, 0.38%, 07/15/25	4.9%
U.S. Treasury Inflation-Indexed Notes, 1.25%, 04/15/28	4.8%
U.S. Treasury Inflation-Indexed Notes, 1.63%, 10/15/27	4.8%

(a)	Excludes short-term securities.

C000166150 [Member]

Shareholder Report [Line Items]

Fund Name

iShares Short-Term TIPS Bond Index Fund

Class Name

Class K Shares

Trading Symbol

BKIPX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about iShares Short-Term TIPS Bond Index Fund (the “Fund”) for the period of January 1, 2024 to June 30, 2024.

Shareholder Report Annual or Semi-Annual

semi-annual shareholder report

Additional Information [Text Block]

You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.

Additional Information Phone Number

(800) 441‑7762

Additional Information Website

blackrock.com/fundreports

Expenses [Text Block]

What were the Fund costs for the last six months?

(based on a hypothetical $10,000 investment)

Class name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
Class K Shares	$3	0.06%

Expenses Paid, Amount

$ 3

Expense Ratio, Percent

0.06%

Performance Past Does Not Indicate Future [Text]

Past performance is not an indication of future results.

Average Annual Return [Table Text Block]

Average annual total returns
	6-Month Total Returns	1 Year	5 Years	Since Inception
Class K Shares	2.36)%	5.35%	3.07)%	2.69%
ICE BofA US Broad Market Index	(0.47)%	2.71%	(0.23)%	1.11%
Bloomberg U.S. Treasury Inflation-Protected Securities (TIPS) 0-5 Years Index (Series-L)	2.26)%	5.37%	3.16)%	2.77%

Performance Inception Date

Feb. 16, 2016

No Deduction of Taxes [Text Block]

Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.

Updated Performance Information Location [Text Block]

Visit blackrock.com for more recent performance information.

Net Assets

$ 299,009,907

Holdings Count | Holding

Investment Company Portfolio Turnover

9.00%

Additional Fund Statistics [Text Block]

Key Fund statistics
Net Assets	$299,009,907%
Number of Portfolio Holdings	$28%
Portfolio Turnover Rate	$9%

Holdings [Text Block]

What did the Fund invest in?

(as of June 30, 2024)

Maturity allocation
Period	Percent of Total Investments^(a)
1-2 Years	23.0%
2-3 Years	23.6%
3-4 Years	27.0%
4-5 Years	26.4%

Five largest holdings
Security	Percent of Total Investments^(a)
U.S. Treasury Inflation-Indexed Notes, 2.38%, 10/15/28	5.6%
U.S. Treasury Inflation-Indexed Notes, 2.13%, 04/15/29	5.0%
U.S. Treasury Inflation-Indexed Notes, 0.38%, 07/15/25	4.9%
U.S. Treasury Inflation-Indexed Notes, 1.25%, 04/15/28	4.8%
U.S. Treasury Inflation-Indexed Notes, 1.63%, 10/15/27	4.8%

(a)	Excludes short-term securities.

Largest Holdings [Text Block]

Five largest holdings
Security	Percent of Total Investments^(a)
U.S. Treasury Inflation-Indexed Notes, 2.38%, 10/15/28	5.6%
U.S. Treasury Inflation-Indexed Notes, 2.13%, 04/15/29	5.0%
U.S. Treasury Inflation-Indexed Notes, 0.38%, 07/15/25	4.9%
U.S. Treasury Inflation-Indexed Notes, 1.25%, 04/15/28	4.8%
U.S. Treasury Inflation-Indexed Notes, 1.63%, 10/15/27	4.8%

(a)	Excludes short-term securities.

C000195948 [Member]

Shareholder Report [Line Items]

Fund Name

iShares Municipal Bond Index Fund

Class Name

Institutional Shares

Trading Symbol

BIDIX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about iShares Municipal Bond Index Fund (the “Fund”) for the period of January 1, 2024 to June 30, 2024.

Shareholder Report Annual or Semi-Annual

semi-annual shareholder report

Additional Information [Text Block]

You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.

Additional Information Phone Number

(800) 441‑7762

Additional Information Website

blackrock.com/fundreports

Expenses [Text Block]

What were the Fund costs for the last six months?

(based on a hypothetical $10,000 investment)

Class name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
Institutional Shares	$12	0.25%

Expenses Paid, Amount

$ 12

Expense Ratio, Percent

0.25%

Performance Past Does Not Indicate Future [Text]

Past performance is not an indication of future results.

Average Annual Return [Table Text Block]

Average annual total returns
	6-Month Total Returns	1 Year	5 Years	10 Years
Institutional Shares	(0.33)%	3.19%	1.09%	2.19%
ICE BofA US Municipal Securities Index	(0.06)%	3.49%	1.19%	2.46%

No Deduction of Taxes [Text Block]

Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.

Updated Performance Information Location [Text Block]

Visit blackrock.com for more recent performance information.

Net Assets

$ 242,270,439

Holdings Count | Holding

269

Investment Company Portfolio Turnover

2.00%

Additional Fund Statistics [Text Block]

Key Fund statistics
Net Assets	$242,270,439%
Number of Portfolio Holdings	$269%
Portfolio Turnover Rate	$2%

Holdings [Text Block]

What did the Fund invest in?

(as of June 30, 2024)

Sector allocation
Sector^(a)	Percent of Total Investments^(b)
Transportation	29.5%
State	26.1%
County/City/Special District/School District	17.8%
Utilities	12.3%
Health	6.8%
Education	6.6%
Housing	0.9%

Credit quality allocation
Credit Rating^(c)	Percent of Total Investments^(b)
AAA/Aaa	21.8%
AA/Aa	59.3%
A	17.6%
BBB/Baa	0.5%
N/R	0.8%

(a)	For purposes of this report, sector sub-classifications may differ from those utilized for compliance purposes.
(b)	Excludes short-term securities.
(c)	For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.

Credit Ratings Selection [Text Block]

For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.

C000195947 [Member]

Shareholder Report [Line Items]

Fund Name

iShares Municipal Bond Index Fund

Class Name

Investor A Shares

Trading Symbol

BIDAX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about iShares Municipal Bond Index Fund (the “Fund”) for the period of January 1, 2024 to June 30, 2024.

Shareholder Report Annual or Semi-Annual

semi-annual shareholder report

Additional Information [Text Block]

You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.

Additional Information Phone Number

(800) 441‑7762

Additional Information Website

blackrock.com/fundreports

Expenses [Text Block]

What were the Fund costs for the last six months?

(based on a hypothetical $10,000 investment)

Class name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
Investor A Shares	$25	0.50%

Expenses Paid, Amount

$ 25

Expense Ratio, Percent

0.50%

Performance Past Does Not Indicate Future [Text]

Past performance is not an indication of future results.

Average Annual Return [Table Text Block]

Average annual total returns
	6-Month Total Returns	1 Year	5 Years	10 Years
Investor A Shares	(0.46)%	2.93%	0.85%	2.04%
ICE BofA US Municipal Securities Index	(0.06)%	3.49%	1.19%	2.46%

No Deduction of Taxes [Text Block]

Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.

Updated Performance Information Location [Text Block]

Visit blackrock.com for more recent performance information.

Net Assets

$ 242,270,439

Holdings Count | Holding

269

Investment Company Portfolio Turnover

2.00%

Additional Fund Statistics [Text Block]

Key Fund statistics
Net Assets	$242,270,439%
Number of Portfolio Holdings	$269%
Portfolio Turnover Rate	$2%

Holdings [Text Block]

What did the Fund invest in?

(as of June 30, 2024)

Sector allocation
Sector^(a)	Percent of Total Investments^(b)
Transportation	29.5%
State	26.1%
County/City/Special District/School District	17.8%
Utilities	12.3%
Health	6.8%
Education	6.6%
Housing	0.9%

Credit quality allocation
Credit Rating^(c)	Percent of Total Investments^(b)
AAA/Aaa	21.8%
AA/Aa	59.3%
A	17.6%
BBB/Baa	0.5%
N/R	0.8%

(a)	For purposes of this report, sector sub-classifications may differ from those utilized for compliance purposes.
(b)	Excludes short-term securities.
(c)	For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.

Credit Ratings Selection [Text Block]

C000201952 [Member]

Shareholder Report [Line Items]

Fund Name

iShares Municipal Bond Index Fund

Class Name

Investor P Shares

Trading Symbol

BIDPX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about iShares Municipal Bond Index Fund (the “Fund”) for the period of January 1, 2024 to June 30, 2024.

Shareholder Report Annual or Semi-Annual

semi-annual shareholder report

Additional Information [Text Block]

You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.

Additional Information Phone Number

(800) 441‑7762

Additional Information Website

blackrock.com/fundreports

Expenses [Text Block]

What were the Fund costs for the last six months?

(based on a hypothetical $10,000 investment)

Class name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
Investor P Shares	$25	0.50%

Expenses Paid, Amount

$ 25

Expense Ratio, Percent

0.50%

Performance Past Does Not Indicate Future [Text]

Past performance is not an indication of future results.

Average Annual Return [Table Text Block]

Average annual total returns
	6-Month Total Returns	1 Year	5 Years	10 Years
Investor P Shares	(0.46)%	2.94)%	0.85%	2.04%
Investor P Shares (with sales charge)	(4.44)%	(1.18)%	0.03%	1.63%
ICE BofA US Municipal Securities Index	(0.06)%	3.49)%	1.19%	2.46%

No Deduction of Taxes [Text Block]

Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.

Updated Performance Information Location [Text Block]

Visit blackrock.com for more recent performance information.

Net Assets

$ 242,270,439

Holdings Count | Holding

269

Investment Company Portfolio Turnover

2.00%

Additional Fund Statistics [Text Block]

Key Fund statistics
Net Assets	$242,270,439%
Number of Portfolio Holdings	$269%
Portfolio Turnover Rate	$2%

Holdings [Text Block]

What did the Fund invest in?

(as of June 30, 2024)

Sector allocation
Sector^(a)	Percent of Total Investments^(b)
Transportation	29.5%
State	26.1%
County/City/Special District/School District	17.8%
Utilities	12.3%
Health	6.8%
Education	6.6%
Housing	0.9%

Credit quality allocation
Credit Rating^(c)	Percent of Total Investments^(b)
AAA/Aaa	21.8%
AA/Aa	59.3%
A	17.6%
BBB/Baa	0.5%
N/R	0.8%

(a)	For purposes of this report, sector sub-classifications may differ from those utilized for compliance purposes.
(b)	Excludes short-term securities.
(c)	For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.

Credit Ratings Selection [Text Block]

C000195949 [Member]

Shareholder Report [Line Items]

Fund Name

iShares Municipal Bond Index Fund

Class Name

Class K Shares

Trading Symbol

BIDKX

Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about iShares Municipal Bond Index Fund (the “Fund”) for the period of January 1, 2024 to June 30, 2024.

Shareholder Report Annual or Semi-Annual

semi-annual shareholder report

Additional Information [Text Block]

You can find additional information about the Fund at blackrock.com/fundreports. You can also request this information by contacting us at (800) 441‑7762.

Additional Information Phone Number

(800) 441‑7762

Additional Information Website

blackrock.com/fundreports

Expenses [Text Block]

What were the Fund costs for the last six months?

(based on a hypothetical $10,000 investment)

Class name	Costs of a $10,000 investment	Costs paid as a percentage of a $10,000 investment
Class K Shares	$10	0.20%

Expenses Paid, Amount

$ 10

Expense Ratio, Percent

0.20%

Performance Past Does Not Indicate Future [Text]

Past performance is not an indication of future results.

Average Annual Return [Table Text Block]

Average annual total returns
	6-Month Total Returns	1 Year	5 Years	10 Years
Class K Shares	(0.31)%	3.24%	1.14%	2.21%
ICE BofA US Municipal Securities Index	(0.06)%	3.49%	1.19%	2.46%

No Deduction of Taxes [Text Block]

Performance results do not reflect the deduction of taxes that a shareholder would pay on fund distributions or on the redemption or sale of fund shares.

Updated Performance Information Location [Text Block]

Visit blackrock.com for more recent performance information.

Net Assets

$ 242,270,439

Holdings Count | Holding

269

Investment Company Portfolio Turnover

2.00%

Additional Fund Statistics [Text Block]

Key Fund statistics
Net Assets	$242,270,439%
Number of Portfolio Holdings	$269%
Portfolio Turnover Rate	$2%

Holdings [Text Block]

What did the Fund invest in?

(as of June 30, 2024)

Sector allocation
Sector^(a)	Percent of Total Investments^(b)
Transportation	29.5%
State	26.1%
County/City/Special District/School District	17.8%
Utilities	12.3%
Health	6.8%
Education	6.6%
Housing	0.9%

Credit quality allocation
Credit Rating^(c)	Percent of Total Investments^(b)
AAA/Aaa	21.8%
AA/Aa	59.3%
A	17.6%
BBB/Baa	0.5%
N/R	0.8%

(a)	For purposes of this report, sector sub-classifications may differ from those utilized for compliance purposes.
(b)	Excludes short-term securities.
(c)	For purposes of this report, credit quality ratings shown above reflect the highest rating assigned by either S&P Global Ratings or Moody’s Investors Service, Inc. if ratings differ. These rating agencies are independent, nationally recognized statistical rating organizations and are widely used. Investment grade ratings are credit ratings of BBB/Baa or higher. Below investment grade ratings are credit ratings of BB/Ba or lower. Investments designated N/R are not rated by either rating agency. Unrated investments do not necessarily indicate low credit quality. Credit quality ratings are subject to change.

Credit Ratings Selection [Text Block]