| Pay vs Performance Disclosure uSD in Thousands | 12 Months Ended |
| Mar. 31, 2023 USD ($) uSD | Mar. 31, 2022 USD ($) uSD | Mar. 31, 2021 USD ($) uSD |
| Pay vs Performance Disclosure [Table] | | | |
| Pay vs Performance [Table Text Block] | Value of Initial Fixed $100 Investment Based On: Fiscal Year Summary Compensation Table Total for PEO ($)(000) (1) Compensation Actually Paid to PEO ($)(000) (1)(2)(3)(4) Average Summary Compensation Table Total for Non-PEO NEOs ($)(000) (1) Average Compensation Actually Paid to Non-PEO NEOs ($)(000) (1)(2)(3)(4) BAH S&P Software & Services Select Industry Index Total Shareholder Return ($) (5) Net Adjusted EBITDA ($)(000) (6) 2023 12,184 15,386 3,673 2,801 142 152 271,215 1,014,065 2022 11,866 9,938 3,125 3,019 132 181 466,577 935,088 2021 8,355 14,801 3,147 5,097 119 192 608,958 839,674 | | |
| Company Selected Measure Name | Adjusted EBITDA | | |
| Named Executive Officers, Footnote [Text Block] | Horacio D. Rozanski is our principal executive officer (PEO) for fiscal years 2021, 2022, and 2023. The individuals comprising the Non-PEO named executive officers (“NEOs”) for each year presented are listed below. 2021 2022 2023 Lloyd W. Howell, Jr. Lloyd W. Howell, Jr. Matthew A. Calderone Karen M. Dahut Karen M. Dahut Kristine Martin Anderson Nancy J. Laben Nancy J. Laben Judith H. Dotson Susan L. Penfield Susan L. Penfield Nancy J. Laben Karen M. Dahut Lloyd W. Howell, Jr. | | |
| Peer Group Issuers, Footnote [Text Block] | Total stockholder return ("TSR") shown in the table above utilizes the S&P Software & Services Select Index which we use in the stock performance graph required by Item 201(e) of Regulation S-K included in the company’s consolidated audited financial statements filed with the SEC on Form 10-K for fiscal years 2021, 2022, and 2023. The comparison assumes $100 was invested for the period starting April 1, 2020 through March 31 of the applicable fiscal year in each of the company’s Common Stock and the S&P Software & Services Select Index. All dollar values assume reinvestment of the pre-tax value of dividends paid by companies included in the S&P Software & Services Select Index. The historical stock price performance of our Common Stock shown is not necessarily indicative of future stock price performance. | | |
| PEO Total Compensation Amount | $ 12,183,785 | $ 11,866,337 | $ 8,355,409 |
| PEO Actually Paid Compensation Amount | $ 15,385,660 | 9,937,722 | 14,800,720 |
| Adjustment To PEO Compensation, Footnote [Text Block] | CAP reflects the exclusions and inclusions of certain amounts from Summary Compensation Table total compensation for the PEO and the other NEOs as set forth below under the heading "Summary Compensation Table Total and Compensation Actually Paid Reconciliation for the PEO and non-PEOs." Equity values are calculated in accordance with FASB ASC Topic 718, Compensation — Stock Compensation. The valuation methodologies and assumptions used to calculate CAP are based on our grant date fair market value of these awards as disclosed in the company’s consolidated audited financial statements filed with the SEC on Form 10-K for the years reflected in the Summary Compensation Table Total, with the adjustments set forth below in the Compensation Actually Paid Reconciliation for the PEO and non-PEOs table. Calculation for PEO Calculation for Average of Non-PEOs Calculation of Compensation Actually Paid Fiscal Year 2021($) Fiscal Year 2022($) Fiscal Year 2023($) Fiscal Year 2021($) Fiscal Year 2022($) Fiscal Year 2023($) SCT Total Compensation 8,355,409 11,866,337 12,183,785 3,147,477 3,124,843 3,673,046 Less aggregate change in actuarial present value of accumulated pension benefits (10,000) (10,000) (10,000) (10,522) (10,373) (8,945) Plus service cost and prior service cost for pension plans — — — — — — Less grant date fair value of stock and option awards in SCT (5,000,076) (8,500,101) (8,500,083) (1,400,071) (1,575,106) (2,201,468) Plus fair value as of fiscal year-end of awards granted during the fiscal year that are outstanding and unvested as of the end of the fiscal year 7,139,821 4,991,758 8,696,165 1,834,004 958,209 1,348,778 Plus change in fair value (whether positive or negative) as of vesting date (from the end of the prior fiscal year) of awards granted in prior fiscal years for which all applicable vesting conditions were satisfied at fiscal year-end or during the fiscal year 1,708,189 563,435 1,013,909 663,256 236,171 152,856 Plus fair value as of vesting date of awards that are granted and vest in the same year 503,796 849,237 909,567 201,506 224,761 132,315 Plus change in fair value (whether positive or negative) as of fiscal year-end for awards granted in prior fiscal years that are outstanding and unvested as of the end of the fiscal year 1,663,419 (225,765) 671,013 540,681 (36,753) 67,845 Less fair value at the end of the prior fiscal year for any awards granted in any prior fiscal year that fail to meet the applicable vesting conditions during the covered fiscal year — — — — — (416,920) Plus dividends or other earnings paid on awards during the fiscal year prior to the vesting date that are not otherwise included in total compensation for the covered fiscal year 440,162 402,820 421,304 120,661 97,072 53,521 Compensation Actually Paid 14,800,720 9,937,722 15,385,660 5,096,992 3,018,825 2,801,027 | | |
| Non-PEO NEO Average Total Compensation Amount | $ 3,673,046 | 3,124,843 | 3,147,477 |
| Non-PEO NEO Average Compensation Actually Paid Amount | $ 2,801,027 | 3,018,825 | 5,096,992 |
| Adjustment to Non-PEO NEO Compensation Footnote [Text Block] | Calculation for PEO Calculation for Average of Non-PEOs Calculation of Compensation Actually Paid Fiscal Year 2021($) Fiscal Year 2022($) Fiscal Year 2023($) Fiscal Year 2021($) Fiscal Year 2022($) Fiscal Year 2023($) SCT Total Compensation 8,355,409 11,866,337 12,183,785 3,147,477 3,124,843 3,673,046 Less aggregate change in actuarial present value of accumulated pension benefits (10,000) (10,000) (10,000) (10,522) (10,373) (8,945) Plus service cost and prior service cost for pension plans — — — — — — Less grant date fair value of stock and option awards in SCT (5,000,076) (8,500,101) (8,500,083) (1,400,071) (1,575,106) (2,201,468) Plus fair value as of fiscal year-end of awards granted during the fiscal year that are outstanding and unvested as of the end of the fiscal year 7,139,821 4,991,758 8,696,165 1,834,004 958,209 1,348,778 Plus change in fair value (whether positive or negative) as of vesting date (from the end of the prior fiscal year) of awards granted in prior fiscal years for which all applicable vesting conditions were satisfied at fiscal year-end or during the fiscal year 1,708,189 563,435 1,013,909 663,256 236,171 152,856 Plus fair value as of vesting date of awards that are granted and vest in the same year 503,796 849,237 909,567 201,506 224,761 132,315 Plus change in fair value (whether positive or negative) as of fiscal year-end for awards granted in prior fiscal years that are outstanding and unvested as of the end of the fiscal year 1,663,419 (225,765) 671,013 540,681 (36,753) 67,845 Less fair value at the end of the prior fiscal year for any awards granted in any prior fiscal year that fail to meet the applicable vesting conditions during the covered fiscal year — — — — — (416,920) Plus dividends or other earnings paid on awards during the fiscal year prior to the vesting date that are not otherwise included in total compensation for the covered fiscal year 440,162 402,820 421,304 120,661 97,072 53,521 Compensation Actually Paid 14,800,720 9,937,722 15,385,660 5,096,992 3,018,825 2,801,027 | | |
| Compensation Actually Paid vs. Total Shareholder Return [Text Block] | | | |
| Compensation Actually Paid vs. Net Income [Text Block] | | | |
| Compensation Actually Paid vs. Company Selected Measure [Text Block] | | | |
| Total Shareholder Return Vs Peer Group [Text Block] | | | |
| Tabular List [Table Text Block] | Metric Metric Type Adjusted EBITDA Financial Measure Revenue Financial Measure Platform Growth Strategic Measure Diversity, Equity & Inclusion (DEI) Strategic Measure | | |
| Total Shareholder Return Amount | $ 142 | 132 | 119 |
| Peer Group Total Shareholder Return Amount | 152 | 181 | 192 |
| Net Income (Loss) | $ 271,215,000 | $ 466,577,000 | $ 608,958,000 |
| Company Selected Measure Amount | uSD | 1,014,065 | 935,088 | 839,674 |
| PEO Name | Horacio D. Rozanski | | |
| Additional 402(v) Disclosure [Text Block] | Amounts shown for CAP are computed in accordance with Item 402(v) of Regulation S-K under the Exchange Act and do not reflect the actual amount of compensation earned by or paid to the NEOs during the applicable year. These amounts reflect total compensation as reported in the Summary Compensation Table with certain adjustments as required by Item 402(v) of Regulation S-K and described in footnote (4) below. (3) For the portion of CAP that is based on year-end stock prices, $92.69 was used for fiscal year 2023, $87.84 was used for fiscal year 2022, and $80.53 was used for fiscal year 2021. | | |
| Measure [Axis]: 1 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Adjusted EBITDA | | |
| Non-GAAP Measure Description [Text Block] | Pursuant to Item 402(v) of Regulation S-K, we determined annual Adjusted EBITDA to be our most important financial performance measure used to link company performance to CAP to our PEO and other NEOs in fiscal year 2023. See Appendix A to this proxy statement for a reconciliation of Adjusted EBITDA to the most directly comparable financial measure calculated and presented in accordance with GAAP. Annually, we review our established performance financial metrics to ensure they maximize stockholder value. As such, we may determine a different financial performance measure in future years. | | |
| Measure [Axis]: 2 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Revenue | | |
| Measure [Axis]: 3 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Platform Growth | | |
| Measure [Axis]: 4 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Diversity, Equity & Inclusion (DEI) | | |
| PEO [Member] | Actuarial Present Value Of Accumulated Pension Benefits [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | $ (10,000) | $ (10,000) | $ (10,000) |
| PEO [Member] | Equity Awards Service Cost And Prior Service Cost [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 0 | 0 |
| PEO [Member] | Equity Awards Grant Date Fair Value Of Stock And Option Awards [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (8,500,083) | (8,500,101) | (5,000,076) |
| PEO [Member] | Equity Awards Granted In The Covered Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 8,696,165 | 4,991,758 | 7,139,821 |
| PEO [Member] | Equity Awards Granted In Prior Years Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 1,013,909 | 563,435 | 1,708,189 |
| PEO [Member] | Equity Awards Granted In Covered Years Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 909,567 | 849,237 | 503,796 |
| PEO [Member] | Equity Awards Granted In Prior Years Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 671,013 | (225,765) | 1,663,419 |
| PEO [Member] | Equity Awards Forfeited During The Covered Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 0 | 0 |
| PEO [Member] | Equity Awards Distribution In The Covered Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 421,304 | 402,820 | 440,162 |
| Non-PEO NEO [Member] | Actuarial Present Value Of Accumulated Pension Benefits [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (8,945) | (10,373) | (10,522) |
| Non-PEO NEO [Member] | Equity Awards Service Cost And Prior Service Cost [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 0 | 0 |
| Non-PEO NEO [Member] | Equity Awards Grant Date Fair Value Of Stock And Option Awards [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (2,201,468) | (1,575,106) | (1,400,071) |
| Non-PEO NEO [Member] | Equity Awards Granted In The Covered Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 1,348,778 | 958,209 | 1,834,004 |
| Non-PEO NEO [Member] | Equity Awards Granted In Prior Years Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 152,856 | 236,171 | 663,256 |
| Non-PEO NEO [Member] | Equity Awards Granted In Covered Years Vested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 132,315 | 224,761 | 201,506 |
| Non-PEO NEO [Member] | Equity Awards Granted In Prior Years Unvested [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 67,845 | (36,753) | 540,681 |
| Non-PEO NEO [Member] | Equity Awards Forfeited During The Covered Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (416,920) | 0 | 0 |
| Non-PEO NEO [Member] | Equity Awards Distribution In The Covered Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | $ 53,521 | $ 97,072 | $ 120,661 |
