Form N-CSR Cover
| Form N-CSR Cover | 12 Months Ended |
| May 31, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | T. ROWE PRICE SHORT-TERM BOND FUND, INC. |
| Entity Central Index Key | 0000731890 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | May 31, 2024 |
Shareholder Report
| Shareholder Report | 12 Months Ended |
| May 31, 2024 USD ($) Holding | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSR |
| Amendment Flag | false |
| Registrant Name | T. ROWE PRICE SHORT-TERM BOND FUND, INC. |
| Entity Central Index Key | 0000731890 |
| Entity Investment Company Type | N-1A |
| Document Period End Date | May 31, 2024 |
| C000225824 | |
| Shareholder Report [Line Items] | |
| Fund Name | Short-Term Bond Fund |
| Class Name | Z Class |
| Trading Symbol | (TRZOX) |
| Annual or Semi-Annual Statement [Text Block] | Annual Shareholder Report |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find the funds prospectus, financial information on Form N-CSR (which includes required tax information for dividends), holdings, proxy voting information, and other information at |
| Expenses [Text Block] | What were the fund costs for the last year? Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Short-Term Bond Fund - Z Class $0 0.00% |
| Expenses Paid, Amount | $ 0 |
| Expense Ratio, Percent | 0% |
| Factors Affecting Performance [Text Block] | What drove fund performance during the past 12 months? The shorter-maturity U.S. investment-grade bond market generated positive returns over the 12-month period ended May 31, 2024, largely lifted by a rally in rates and credit spreads near the end of 2023. The funds overweight to investment-grade corporate bonds and corresponding underweight to U.S. Treasuries aided performance relative to its style-specific benchmark, the Bloomberg 13 Year U.S. Government/Credit Bond Index, as corporate credit spreads tightened. Out-of-benchmark allocations to residential mortgage-backed securities, asset-backed securities (ABS), and commercial mortgage-backed securities also contributed as the securitized sectors benefited from the rally in U.S. Treasury yields and strong investor demand. Allocations along the yield curve slightly hindered relative performance. An overweight to the five-year key rate detracted as the yield on the five-year U.S. Treasury note ended the period higher. The fund seeks to provide a high level of income with minimal fluctuation in principal value and liquidity by investing in a diversified portfolio. The funds allocation to investment-grade corporate bonds decreased over the reporting period but continued to represent its largest absolute and relative positions. We focused on additions in securitized sectors, notably ABS, and our allocation in those sectors ended higher. While we are primarily a cash bond manager, we occasionally employ the limited use of derivatives in our strategy for hedging purposes. The use of derivatives may include futures and options, as well as credit default and interest rate swaps. During the reporting period, our use of derivativesspecifically, interest rate derivativesdetracted from absolute performance. |
| Average Annual Return [Table Text Block] | Average Annual Total Returns 1 Year Since Inception 2/22/2021 Short-Term Bond Fund (Z Class) 5.12 % 0.80 % Bloomberg U.S. Aggregate Bond Index (Regulatory Benchmark) 1.31 - Bloomberg 1-3 Year U.S. Government/Credit Bond Index (Strategy Benchmark) 3.86 0.32 The preceding line graph shows the value of a hypothetical $10,000 investment in the fund over the past 10 fiscal year periods or since inception (for funds lacking 10-year records). The funds performance information included in the line graph and table above is compared with a regulatory required index that represents an overall securities market (Regulatory Benchmark). In addition, the line graph and table may also include one or more indexes that more closely aligns to the fund's investment strategy (Strategy Benchmark(s)). Due to new SEC Rules on shareholder reporting the fund adopted a new broad-based securities market index, referred to as the Regulatory Benchmark. Market index returns do not include expenses, which are deducted from fund returns. The fund's total return figures reflect the reinvestment of dividends and capital gains, if any. Neither the funds returns nor the index returns reflect the deduction of taxes that a shareholder would pay on fund distributions or redemptions of fund shares. The funds past performance is not a good predictor of the funds future performance. www.troweprice.com |
| AssetsNet | $ 4,686,925,000 |
| Holdings Count | Holding | 881 |
| Advisory Fees Paid, Amount | $ 12,879,000 |
| InvestmentCompanyPortfolioTurnover | 92.30% |
| Additional Fund Statistics [Text Block] | What are some fund statistics? Fund Statistics Total Net Assets (000s) $4,686,925 Number of Portfolio Holdings 881 |
| Holdings [Text Block] | Credit Quality Allocation* AAA Rated 15.9 % AA Rated 9.7 A Rated 20.7 BBB Rated 25.1 BB Rated and Below 0.1 Not Rated 2.7 U.S. Government Agency Securities 4.5 U.S. Treasury Securities 20.9 Reserves 0.4 *Credit ratings for the securities held in the Fund are provided by Moodys, Standard & Poors, and Fitch and are converted to the Standard & Poors nomenclature. A rating of AAA represents the highest-rated securities, and a rating of D represents the lowest rated securities. If the ratings agencies differ, the highest rating is applied to the security. If a rating is not available, the security is classified as Not Rated. The rating of the underlying investment vehicle is used to determine the creditworthiness of credit default swaps and sovereign securities. The Fund is not rated by any agency. |
| Largest Holdings [Text Block] | Top Ten Holdings U.S. Treasury Notes 19.9 % Federal National Mortgage Assn. 2.6 U.S. Treasury Inflation-Indexed Notes 1.0 Government National Mortgage Assn. 1.0 AbbVie 0.8 Crown Castle 0.8 Federal Home Loan Mortgage 0.8 JPMorgan Chase 0.8 CarMax Auto Owner Trust 0.8 Verus Securitization Trust 0.8 |
| Material Fund Change [Text Block] | |
| C000005536 | |
| Shareholder Report [Line Items] | |
| Fund Name | Short-Term Bond Fund |
| Class Name | Investor Class |
| Trading Symbol | (PRWBX) |
| Annual or Semi-Annual Statement [Text Block] | Annual Shareholder Report |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find the funds prospectus, financial information on Form N-CSR (which includes required tax information for dividends), holdings, proxy voting information, and other information at |
| Expenses [Text Block] | What were the fund costs for the last year? Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Short-Term Bond Fund - Investor Class $48 0.47% |
| Expenses Paid, Amount | $ 48 |
| Expense Ratio, Percent | 0.47% |
| Factors Affecting Performance [Text Block] | What drove fund performance during the past 12 months? The shorter-maturity U.S. investment-grade bond market generated positive returns over the 12-month period ended May 31, 2024, largely lifted by a rally in rates and credit spreads near the end of 2023. The funds overweight to investment-grade corporate bonds and corresponding underweight to U.S. Treasuries aided performance relative to its style-specific benchmark, the Bloomberg 13 Year U.S. Government/Credit Bond Index, as corporate credit spreads tightened. Out-of-benchmark allocations to residential mortgage-backed securities, asset-backed securities (ABS), and commercial mortgage-backed securities also contributed as the securitized sectors benefited from the rally in U.S. Treasury yields and strong investor demand. Allocations along the yield curve slightly hindered relative performance. An overweight to the five-year key rate detracted as the yield on the five-year U.S. Treasury note ended the period higher. The fund seeks to provide a high level of income with minimal fluctuation in principal value and liquidity by investing in a diversified portfolio. The funds allocation to investment-grade corporate bonds decreased over the reporting period but continued to represent its largest absolute and relative positions. We focused on additions in securitized sectors, notably ABS, and our allocation in those sectors ended higher. While we are primarily a cash bond manager, we occasionally employ the limited use of derivatives in our strategy for hedging purposes. The use of derivatives may include futures and options, as well as credit default and interest rate swaps. During the reporting period, our use of derivativesspecifically, interest rate derivativesdetracted from absolute performance. |
| Average Annual Return [Table Text Block] | Average Annual Total Returns 1 Year 5 Years 10 Years Short-Term Bond Fund (Investor Class) 4.63 % 1.53 % 1.47 % Bloomberg U.S. Aggregate Bond Index (Regulatory Benchmark) 1.31 - 1.26 Bloomberg 1-3 Year U.S. Government/Credit Bond Index (Strategy Benchmark) 3.86 1.25 1.29 The preceding line graph shows the value of a hypothetical $10,000 investment in the fund over the past 10 fiscal year periods or since inception (for funds lacking 10-year records). The funds performance information included in the line graph and table above is compared with a regulatory required index that represents an overall securities market (Regulatory Benchmark). In addition, the line graph and table may also include one or more indexes that more closely aligns to the fund's investment strategy (Strategy Benchmark(s)). Due to new SEC Rules on shareholder reporting the fund adopted a new broad-based securities market index, referred to as the Regulatory Benchmark. Market index returns do not include expenses, which are deducted from fund returns. The fund's total return figures reflect the reinvestment of dividends and capital gains, if any. Neither the funds returns nor the index returns reflect the deduction of taxes that a shareholder would pay on fund distributions or redemptions of fund shares. The funds past performance is not a good predictor of the funds future performance. www.troweprice.com |
| AssetsNet | $ 4,686,925,000 |
| Holdings Count | Holding | 881 |
| Advisory Fees Paid, Amount | $ 12,879,000 |
| InvestmentCompanyPortfolioTurnover | 92.30% |
| Additional Fund Statistics [Text Block] | What are some fund statistics? Fund Statistics Total Net Assets (000s) $4,686,925 Number of Portfolio Holdings 881 |
| Holdings [Text Block] | Credit Quality Allocation* AAA Rated 15.9 % AA Rated 9.7 A Rated 20.7 BBB Rated 25.1 BB Rated and Below 0.1 Not Rated 2.7 U.S. Government Agency Securities 4.5 U.S. Treasury Securities 20.9 Reserves 0.4 *Credit ratings for the securities held in the Fund are provided by Moodys, Standard & Poors, and Fitch and are converted to the Standard & Poors nomenclature. A rating of AAA represents the highest-rated securities, and a rating of D represents the lowest rated securities. If the ratings agencies differ, the highest rating is applied to the security. If a rating is not available, the security is classified as Not Rated. The rating of the underlying investment vehicle is used to determine the creditworthiness of credit default swaps and sovereign securities. The Fund is not rated by any agency. |
| Largest Holdings [Text Block] | Top Ten Holdings U.S. Treasury Notes 19.9 % Federal National Mortgage Assn. 2.6 U.S. Treasury Inflation-Indexed Notes 1.0 Government National Mortgage Assn. 1.0 AbbVie 0.8 Crown Castle 0.8 Federal Home Loan Mortgage 0.8 JPMorgan Chase 0.8 CarMax Auto Owner Trust 0.8 Verus Securitization Trust 0.8 |
| Material Fund Change [Text Block] | |
| C000005537 | |
| Shareholder Report [Line Items] | |
| Fund Name | Short-Term Bond Fund |
| Class Name | Advisor Class |
| Trading Symbol | (PASHX) |
| Annual or Semi-Annual Statement [Text Block] | Annual Shareholder Report |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find the funds prospectus, financial information on Form N-CSR (which includes required tax information for dividends), holdings, proxy voting information, and other information at |
| Expenses [Text Block] | What were the fund costs for the last year? Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Short-Term Bond Fund - Advisor Class $80 0.78% |
| Expenses Paid, Amount | $ 80 |
| Expense Ratio, Percent | 0.78% |
| Factors Affecting Performance [Text Block] | What drove fund performance during the past 12 months? The shorter-maturity U.S. investment-grade bond market generated positive returns over the 12-month period ended May 31, 2024, largely lifted by a rally in rates and credit spreads near the end of 2023. The funds overweight to investment-grade corporate bonds and corresponding underweight to U.S. Treasuries aided performance relative to its style-specific benchmark, the Bloomberg 13 Year U.S. Government/Credit Bond Index, as corporate credit spreads tightened. Out-of-benchmark allocations to residential mortgage-backed securities, asset-backed securities (ABS), and commercial mortgage-backed securities also contributed as the securitized sectors benefited from the rally in U.S. Treasury yields and strong investor demand. Allocations along the yield curve slightly hindered relative performance. An overweight to the five-year key rate detracted as the yield on the five-year U.S. Treasury note ended the period higher. The fund seeks to provide a high level of income with minimal fluctuation in principal value and liquidity by investing in a diversified portfolio. The funds allocation to investment-grade corporate bonds decreased over the reporting period but continued to represent its largest absolute and relative positions. We focused on additions in securitized sectors, notably ABS, and our allocation in those sectors ended higher. While we are primarily a cash bond manager, we occasionally employ the limited use of derivatives in our strategy for hedging purposes. The use of derivatives may include futures and options, as well as credit default and interest rate swaps. During the reporting period, our use of derivativesspecifically, interest rate derivativesdetracted from absolute performance. |
| Average Annual Return [Table Text Block] | Average Annual Total Returns 1 Year 5 Years 10 Years Short-Term Bond Fund (Advisor Class) 4.30 % 1.28 % 1.19 % Bloomberg U.S. Aggregate Bond Index (Regulatory Benchmark) 1.31 - 1.26 Bloomberg 1-3 Year U.S. Government/Credit Bond Index (Strategy Benchmark) 3.86 1.25 1.29 The preceding line graph shows the value of a hypothetical $10,000 investment in the fund over the past 10 fiscal year periods or since inception (for funds lacking 10-year records). The funds performance information included in the line graph and table above is compared with a regulatory required index that represents an overall securities market (Regulatory Benchmark). In addition, the line graph and table may also include one or more indexes that more closely aligns to the fund's investment strategy (Strategy Benchmark(s)). Due to new SEC Rules on shareholder reporting the fund adopted a new broad-based securities market index, referred to as the Regulatory Benchmark. Market index returns do not include expenses, which are deducted from fund returns. The fund's total return figures reflect the reinvestment of dividends and capital gains, if any. Neither the funds returns nor the index returns reflect the deduction of taxes that a shareholder would pay on fund distributions or redemptions of fund shares. The funds past performance is not a good predictor of the funds future performance. www.troweprice.com |
| AssetsNet | $ 4,686,925,000 |
| Holdings Count | Holding | 881 |
| Advisory Fees Paid, Amount | $ 12,879,000 |
| InvestmentCompanyPortfolioTurnover | 92.30% |
| Additional Fund Statistics [Text Block] | What are some fund statistics? Fund Statistics Total Net Assets (000s) $4,686,925 Number of Portfolio Holdings 881 |
| Holdings [Text Block] | Credit Quality Allocation* AAA Rated 15.9 % AA Rated 9.7 A Rated 20.7 BBB Rated 25.1 BB Rated and Below 0.1 Not Rated 2.7 U.S. Government Agency Securities 4.5 U.S. Treasury Securities 20.9 Reserves 0.4 *Credit ratings for the securities held in the Fund are provided by Moodys, Standard & Poors, and Fitch and are converted to the Standard & Poors nomenclature. A rating of AAA represents the highest-rated securities, and a rating of D represents the lowest rated securities. If the ratings agencies differ, the highest rating is applied to the security. If a rating is not available, the security is classified as Not Rated. The rating of the underlying investment vehicle is used to determine the creditworthiness of credit default swaps and sovereign securities. The Fund is not rated by any agency. |
| Largest Holdings [Text Block] | Top Ten Holdings U.S. Treasury Notes 19.9 % Federal National Mortgage Assn. 2.6 U.S. Treasury Inflation-Indexed Notes 1.0 Government National Mortgage Assn. 1.0 AbbVie 0.8 Crown Castle 0.8 Federal Home Loan Mortgage 0.8 JPMorgan Chase 0.8 CarMax Auto Owner Trust 0.8 Verus Securitization Trust 0.8 |
| Material Fund Change [Text Block] | |
| C000166333 | |
| Shareholder Report [Line Items] | |
| Fund Name | Short-Term Bond Fund |
| Class Name | I Class |
| Trading Symbol | (TBSIX) |
| Annual or Semi-Annual Statement [Text Block] | Annual Shareholder Report |
| Shareholder Report Annual or Semi-Annual | annual shareholder report |
| Additional Information [Text Block] | You can find the funds prospectus, financial information on Form N-CSR (which includes required tax information for dividends), holdings, proxy voting information, and other information at |
| Expenses [Text Block] | What were the fund costs for the last year? Costs of a $10,000 investment Costs paid as a percentage of a $10,000 investment Short-Term Bond Fund - I Class $35 0.34% |
| Expenses Paid, Amount | $ 35 |
| Expense Ratio, Percent | 0.34% |
| Factors Affecting Performance [Text Block] | What drove fund performance during the past 12 months? The shorter-maturity U.S. investment-grade bond market generated positive returns over the 12-month period ended May 31, 2024, largely lifted by a rally in rates and credit spreads near the end of 2023. The funds overweight to investment-grade corporate bonds and corresponding underweight to U.S. Treasuries aided performance relative to its style-specific benchmark, the Bloomberg 13 Year U.S. Government/Credit Bond Index, as corporate credit spreads tightened. Out-of-benchmark allocations to residential mortgage-backed securities, asset-backed securities (ABS), and commercial mortgage-backed securities also contributed as the securitized sectors benefited from the rally in U.S. Treasury yields and strong investor demand. Allocations along the yield curve slightly hindered relative performance. An overweight to the five-year key rate detracted as the yield on the five-year U.S. Treasury note ended the period higher. The fund seeks to provide a high level of income with minimal fluctuation in principal value and liquidity by investing in a diversified portfolio. The funds allocation to investment-grade corporate bonds decreased over the reporting period but continued to represent its largest absolute and relative positions. We focused on additions in securitized sectors, notably ABS, and our allocation in those sectors ended higher. While we are primarily a cash bond manager, we occasionally employ the limited use of derivatives in our strategy for hedging purposes. The use of derivatives may include futures and options, as well as credit default and interest rate swaps. During the reporting period, our use of derivativesspecifically, interest rate derivativesdetracted from absolute performance. |
| Average Annual Return [Table Text Block] | Average Annual Total Returns 1 Year 5 Years Since Inception 12/17/2015 Short-Term Bond Fund (I Class) 4.76 % 1.64 % 1.84 % Bloomberg U.S. Aggregate Bond Index (Regulatory Benchmark) 1.31 - 1.17 Bloomberg 1-3 Year U.S. Government/Credit Bond Index (Strategy Benchmark) 3.86 1.25 1.44 The preceding line graph shows the value of a hypothetical $500,000 investment in the fund over the past 10 fiscal year periods or since inception (for funds lacking 10-year records). The funds performance information included in the line graph and table above is compared with a regulatory required index that represents an overall securities market (Regulatory Benchmark). In addition, the line graph and table may also include one or more indexes that more closely aligns to the fund's investment strategy (Strategy Benchmark(s)). Due to new SEC Rules on shareholder reporting the fund adopted a new broad-based securities market index, referred to as the Regulatory Benchmark. Market index returns do not include expenses, which are deducted from fund returns. The fund's total return figures reflect the reinvestment of dividends and capital gains, if any. Neither the funds returns nor the index returns reflect the deduction of taxes that a shareholder would pay on fund distributions or redemptions of fund shares. The funds past performance is not a good predictor of the funds future performance. www.troweprice.com |
| AssetsNet | $ 4,686,925,000 |
| Holdings Count | Holding | 881 |
| Advisory Fees Paid, Amount | $ 12,879,000 |
| InvestmentCompanyPortfolioTurnover | 92.30% |
| Additional Fund Statistics [Text Block] | What are some fund statistics? Fund Statistics Total Net Assets (000s) $4,686,925 Number of Portfolio Holdings 881 |
| Holdings [Text Block] | Credit Quality Allocation* AAA Rated 15.9 % AA Rated 9.7 A Rated 20.7 BBB Rated 25.1 BB Rated and Below 0.1 Not Rated 2.7 U.S. Government Agency Securities 4.5 U.S. Treasury Securities 20.9 Reserves 0.4 *Credit ratings for the securities held in the Fund are provided by Moodys, Standard & Poors, and Fitch and are converted to the Standard & Poors nomenclature. A rating of AAA represents the highest-rated securities, and a rating of D represents the lowest rated securities. If the ratings agencies differ, the highest rating is applied to the security. If a rating is not available, the security is classified as Not Rated. The rating of the underlying investment vehicle is used to determine the creditworthiness of credit default swaps and sovereign securities. The Fund is not rated by any agency. |
| Largest Holdings [Text Block] | Top Ten Holdings U.S. Treasury Notes 19.9 % Federal National Mortgage Assn. 2.6 U.S. Treasury Inflation-Indexed Notes 1.0 Government National Mortgage Assn. 1.0 AbbVie 0.8 Crown Castle 0.8 Federal Home Loan Mortgage 0.8 JPMorgan Chase 0.8 CarMax Auto Owner Trust 0.8 Verus Securitization Trust 0.8 |
| Material Fund Change [Text Block] |
Shareholder Report, Average Ann
| Shareholder Report, Average Annual Return (Details) | 12 Months Ended | 39 Months Ended | 60 Months Ended | 101 Months Ended | 120 Months Ended |
| May 31, 2024 | May 31, 2024 | May 31, 2024 | May 31, 2024 | May 31, 2024 | |
| Without Sales Load [Member] | C000225824 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 5.12% | 0.80% | |||
| Without Sales Load [Member] | C000005536 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 4.63% | 1.53% | 1.47% | ||
| Without Sales Load [Member] | C000005537 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 4.30% | 1.28% | 1.19% | ||
| Without Sales Load [Member] | C000166333 | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 4.76% | 1.64% | 1.84% | ||
| Bloomberg U.S. Aggregate Bond Index | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 1.31% | (2.93%) | |||
| Bloomberg U.S. Aggregate Bond Index | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 1.31% | (0.17%) | 1.26% | ||
| Bloomberg U.S. Aggregate Bond Index | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 1.31% | (0.17%) | 1.26% | ||
| Bloomberg U.S. Aggregate Bond Index | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 1.31% | (0.17%) | 1.17% | ||
| Bloomberg 1-3 Year U.S. Government/Credit Bond Index | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 3.86% | 0.32% | |||
| Bloomberg 1-3 Year U.S. Government/Credit Bond Index | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 3.86% | 1.25% | 1.29% | ||
| Bloomberg 1-3 Year U.S. Government/Credit Bond Index | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 3.86% | 1.25% | 1.29% | ||
| Bloomberg 1-3 Year U.S. Government/Credit Bond Index | |||||
| Average Annual Return [Line Items] | |||||
| Average Annual Return, Percent | 3.86% | 1.25% | 1.44% |
Shareholder Report, Holdings (D
| Shareholder Report, Holdings (Details) | May 31, 2024 |
| C000225824 | AAA Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15.90% |
| C000225824 | AA Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.70% |
| C000225824 | A Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.70% |
| C000225824 | BBB Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 25.10% |
| C000225824 | BB Rated and Below | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000225824 | Not Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| C000225824 | U.S. Government Agency Securities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.50% |
| C000225824 | U.S. Treasury Securities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.90% |
| C000005536 | AAA Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15.90% |
| C000005536 | AA Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.70% |
| C000005536 | A Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.70% |
| C000005536 | BBB Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 25.10% |
| C000005536 | BB Rated and Below | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000005536 | Not Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| C000005536 | U.S. Government Agency Securities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.50% |
| C000005536 | U.S. Treasury Securities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.90% |
| C000005537 | AAA Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15.90% |
| C000005537 | AA Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.70% |
| C000005537 | A Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.70% |
| C000005537 | BBB Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 25.10% |
| C000005537 | BB Rated and Below | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000005537 | Not Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| C000005537 | U.S. Government Agency Securities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.50% |
| C000005537 | U.S. Treasury Securities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.90% |
| C000166333 | AAA Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15.90% |
| C000166333 | AA Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 9.70% |
| C000166333 | A Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.70% |
| C000166333 | BBB Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 25.10% |
| C000166333 | BB Rated and Below | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.10% |
| C000166333 | Not Rated | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| C000166333 | U.S. Government Agency Securities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.50% |
| C000166333 | U.S. Treasury Securities | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.90% |