Booz Allen Hamilton Holding (BAH) 10-Q 29 Oct 18 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Sep. 30, 2018	Oct. 24, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	Booz Allen Hamilton Holding Corp
Entity Central Index Key	1,443,646
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,019
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--03-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Class A Common Stock
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		142,343,338
Non-voting common stock, Class B
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		0
Restricted common stock, Class C
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		0
Special voting common stock, Class E
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		0

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Current assets:
Cash and cash equivalents	$ 342,586	$ 286,958
Accounts receivable, net of allowance	1,165,326	1,133,705
Prepaid expenses and other current assets	93,985	71,309
Total current assets	1,601,897	1,491,972
Property and equipment, net of accumulated depreciation	152,264	152,364
Intangible assets, net of accumulated amortization	287,949	278,504
Goodwill	1,581,160	1,581,146
Other long-term assets	112,116	102,633
Total assets	3,735,386	3,606,619
Current liabilities:
Current portion of long-term debt	63,100	63,100
Accounts payable and other accrued expenses	638,262	557,559
Accrued compensation and benefits	271,961	282,750
Other current liabilities	131,475	125,358
Total current liabilities	1,104,798	1,028,767
Long-term debt, net of current portion	1,723,699	1,755,479
Other long-term liabilities	260,549	259,882
Total liabilities	3,089,046	3,044,128
Commitments and contingencies (Note 18)
Stockholders’ equity:
Common stock, Class A — $0.01 par value — authorized, 600,000,000 shares; issued, 159,124,212 shares at September 30, 2018 and 158,028,673 shares at March 31, 2018; outstanding, 142,550,779 shares at September 30, 2018 and 143,446,539 shares at March 31, 2018	1,591	1,580
Treasury stock, at cost — 16,573,433 shares at September 30, 2018 and 14,582,134 shares at March 31, 2018	(550,688)	(461,457)
Additional paid-in capital	373,980	346,958
Retained earnings	832,774	690,516
Accumulated other comprehensive loss	(11,317)	(15,106)
Total stockholders’ equity	646,340	562,491
Total liabilities and stockholders’ equity	$ 3,735,386	$ 3,606,619

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2018	Mar. 31, 2018
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	600,000,000	600,000,000
Common stock, shares issued	159,124,212	158,028,673
Common stock, shares outstanding	142,550,779	143,446,539
Treasury stock, shares	16,573,433	14,582,134

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenue	$ 1,613,997	$ 1,542,805	$ 3,260,845	$ 3,065,815
Operating costs and expenses:
Cost of revenue	748,570	696,691	1,534,382	1,432,484
Billable expenses	478,349	483,556	955,784	935,220
General and administrative expenses	226,901	213,623	432,737	407,062
Depreciation and amortization	16,426	16,046	32,579	31,495
Total operating costs and expenses	1,470,246	1,409,916	2,955,482	2,806,261
Operating income	143,751	132,889	305,363	259,554
Interest expense	(22,247)	(20,958)	(45,321)	(39,705)
Other income (expense), net	(1,617)	(1,338)	(2,788)	(2,479)
Income before income taxes	119,887	110,593	257,254	217,370
Income tax expense	27,174	36,946	60,337	73,111
Net income	$ 92,713	$ 73,647	$ 196,917	$ 144,259
Earnings per common share (Note 3):
Basic (in dollars per share)	$ 0.65	$ 0.50	$ 1.37	$ 0.97
Diluted (in dollars per share)	0.64	0.49	1.36	0.96
Dividends declared per share (in dollars per share)	$ 0.19	$ 0.17	$ 0.38	$ 0.34

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 92,713	$ 73,647	$ 196,917	$ 144,259
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Change in unrealized gain (loss) on derivatives designated as cash flow hedges	1,038	(124)	2,958	(634)
Change in postretirement plan costs	424	361	831	724
Total other comprehensive income (loss), net of tax	1,462	237	3,789	90
Comprehensive income	$ 94,175	$ 73,884	$ 200,706	$ 144,349

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018
Cash flows from operating activities
Net income	$ 196,917	$ 144,259
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	32,579	31,495
Stock-based compensation expense	13,264	11,595
Excess tax benefits from stock-based compensation	(6,111)	(9,289)
Amortization of debt issuance costs and loss on extinguishment	6,920	2,633
Losses on dispositions	408	723
Changes in assets and liabilities:
Accounts receivable	(31,621)	(60,380)
Prepaid expenses and other current assets	(7,170)	3,300
Other long-term assets	(19,663)	(1,444)
Accrued compensation and benefits	(3,154)	(9,903)
Accounts payable and other accrued expenses	80,595	57,365
Accrued interest	123	7,154
Other current liabilities	8,206	(11,646)
Other long-term liabilities	3,274	12,200
Net cash provided by operating activities	274,567	178,062
Cash flows from investing activities
Purchases of property, equipment, and software	(39,672)	(36,989)
Payments for business acquisitions, net of cash acquired	(20)	(204)
Net cash used in investing activities	(39,692)	(37,193)
Cash flows from financing activities
Proceeds from issuance of common stock	5,227	4,028
Stock option exercises	8,542	6,267
Repurchases of common stock	(98,377)	(168,498)
Cash dividends paid	(54,660)	(50,866)
Dividend equivalents paid to option holders	(267)	(890)
Repayment of debt	(101,550)	(191,575)
Proceeds from debt issuance	62,072	373,291
Payment on contingent liabilities from acquisition	(234)	0
Net cash used in financing activities	(179,247)	(28,243)
Net increase in cash and cash equivalents	55,628	112,626
Cash and cash equivalents––beginning of period	286,958	217,417	$ 217,417
Cash and cash equivalents––end of period	342,586	330,043	286,958
Cash paid during the period for:
Interest	38,140	25,802
Income taxes	74,275	$ 82,035
Supplemental disclosures of non-cash investing and financing activities
Noncash financing activities	$ 2,658		$ 0

Business Overview

Business Overview	6 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business Overview	BUSINESS OVERVIEW Organization Booz Allen Hamilton Holding Corporation, including its wholly owned subsidiaries, or the Company, we, us, and our, was incorporated in Delaware in May 2008. The Company provides management and technology consulting, engineering, analytics, digital solutions, mission operations, and cyber expertise to U.S. and international governments, major corporations, and not-for-profit organizations. The Company reports operating results and financial data in one reportable segment. The Company is headquartered in McLean, Virginia, with approximately 25,300 employees as of September 30, 2018 .

Basis of Presentation

Basis of Presentation	6 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	BASIS OF PRESENTATION The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or GAAP, and pursuant to the rules and regulations of the U.S. Securities and Exchange Commission, or SEC, and should be read in conjunction with the information contained in the Company's Annual Report on Form 10-K for the year ended March 31, 2018. The interim period unaudited condensed consolidated financial statements are presented as described below. Certain information and disclosures normally required for annual financial statements have been condensed or omitted pursuant to GAAP and SEC rules and regulations. In the opinion of management, all adjustments considered necessary for fair presentation of the results of the interim period presented have been included. The Company’s fiscal year ends on March 31 and unless otherwise noted, references to fiscal year or fiscal are for fiscal years ended March 31. The results of operations for the six months ended September 30, 2018 are not necessarily indicative of results to be expected for the full fiscal year. The condensed consolidated financial statements and notes of the Company include its subsidiaries, and the joint ventures and partnerships over which the Company has a controlling financial interest. The Company uses the equity method to account for investments in entities that it does not control if it is otherwise able to exert significant influence over the entities' operating and financial policies. Effective April 1, 2018, the Company adopted Accounting Standards Codification (ASC) No. 606, Revenue from Contracts with Customers (Topic 606), and Accounting Standard Updates (ASU) 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost , on a full retrospective method for all amounts and percentages presented and disclosures set forth in this Form 10-Q. Certain amounts reported in the Company's prior year condensed consolidated financial statements have been reclassified to conform to the current year presentation. Accounting Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expenses during the reporting periods. Areas of the financial statements where estimates may have the most significant effect include contractual and regulatory reserves, valuation and lives of tangible and intangible assets, contingent consideration related to business acquisitions, impairment of long-lived assets, accrued liabilities, revenue recognition, including the accrual of indirect costs, bonus and other incentive compensation, stock-based compensation, reserves for tax benefits and valuation allowances on deferred tax assets, provisions for income taxes, postretirement obligations, certain deferred costs, collectability of receivables, and loss accruals for litigation. Actual results experienced by the Company may differ materially from management's estimates. Recently Adopted Accounting Standards The Company has accounted for the tax effects of the Tax Cuts and Jobs Act, or the 2017 Tax Act, under the guidance of Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act, or SAB 118, on a provisional basis as of the fourth quarter of fiscal 2018. During the three months ended September 30, 2018 , the Company continued its assessment of the 2017 Tax Act, including the potential accounting impact for any new guidance issued during the quarter. The Company made immaterial provisional adjustments associated with the limitation on the deductibility of certain executive compensation based on its preliminary assessment of the recently issued IRS Notice 2018-68. There were no additional changes to the provisional amounts recorded at March 31, 2018. The Company expects to complete its accounting assessment within the prescribed measurement period. See Note 10 to our consolidated financial statements for further information regarding the updated effects of the 2017 Tax Act during the second quarter of fiscal 2019. In May 2014, the Financial Accounting Standards Board, or FASB, issued Accounting Standard Codification No. 606, Revenue from Contracts with Customers (Topic 606). Topic 606, as amended, replaced existing revenue recognition standards by outlining a single set of comprehensive principles for recognizing revenue. The revenue standard also significantly expanded the disclosure requirements for revenue arrangements. Amendments to Topic 606 have generally focused on promoting a more consistent interpretation and application of the principles for recognizing revenue. Topic 606 was effective for the Company beginning on April 1, 2018 (i.e., beginning with the first quarter fiscal 2019 interim financial statements). The Company adopted the new revenue standard using the full retrospective transition method, which requires that it be applied to each prior reporting period presented and that the cumulative effect of applying the standard be recognized at the earliest period presented (i.e., April 1, 2016, the beginning of the first quarter of fiscal 2017). During fiscal 2018, the Company completed its assessment of the cumulative effect of adopting Topic 606 and assessed the impact to be immaterial as of the date of adoption. The cumulative impact on our retained earnings for the earliest period presented of April 1, 2016 was an increase of $2.9 million . Thereafter, the adoption of Topic 606 increased our fiscal 2017 retained earnings by $8.4 million and decreased our fiscal 2018 retained earnings by $3.4 million , resulting in a cumulative impact on our retained earnings of $7.9 million as of April 1, 2018. The impact of Topic 606 on fiscal 2017 and 2018 results may not be representative of the impact on subsequent years’ results. For more information on the notable impacts of the adoption of Topic 606 on the Company's accounting policies, practices, estimates, and significant judgments, refer to the Company's Annual Report on Form 10-K for the year ended March 31, 2018 and Note 3, Revenue Recognition. The Company also retrospectively adopted ASU 2017-07, which changed the presentation of net periodic benefit cost components on the condensed consolidated statement of operations. Under this guidance, the service cost component of net periodic benefit cost continues to be presented consistent with other employee compensation costs and within operating income, while the remaining components of net periodic benefit costs are excluded from operating income. As a result, $1.9 million and $3.8 million of net periodic benefit costs related to non-service components, for the three and six months ended September 30, 2017 respectively, were reclassified to Other income (expense), net in the condensed consolidated statement of operations in the second quarter of fiscal 2018. The Company's previously issued condensed consolidated financial statements have been adjusted for the retrospective adoption of both Topic 606 and ASU 2017-07, as summarized in the following table: Three Months Ended September 30, 2017 Six Months Ended September 30, 2017 Effect of Adoption Effect of Adoption As Reported Topic 606 ASU 2017-07 As Adjusted As Reported Topic 606 ASU 2017-07 As Adjusted Revenue $ 1,542,085 $ 720 $ — $ 1,542,805 $ 3,035,655 $ 30,160 $ — $ 3,065,815 Operating income 126,486 4,502 1,901 132,889 265,950 (10,199 ) 3,803 259,554 Income before income taxes 106,091 4,502 — 110,593 227,569 (10,199 ) — 217,370 Net income $ 70,913 $ 2,734 $ — $ 73,647 $ 150,453 $ (6,194 ) $ — $ 144,259 Earnings per common share (Note 4): Basic $ 0.48 $ 0.02 $ — $ 0.50 $ 1.01 $ (0.04 ) $ — $ 0.97 Diluted $ 0.47 $ 0.02 $ — $ 0.49 $ 1.00 $ (0.04 ) $ — $ 0.96 Recent Accounting Pronouncements Not Yet Adopted In August 2018, the FASB issued ASU No. 2018-15, Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract . This guidance requires a customer in a cloud computing arrangement that is a service contract to follow existing internal-use software guidance to determine which implementation costs to defer and recognize as an asset. ASU 2018-15 generally aligns the guidance on capitalizing implementation costs incurred in a cloud computing arrangement that is a service contract with that of implementation costs incurred to develop or obtain internal-use software, including hosting arrangements that include an internal-use software license. ASU 2018-15 is effective for interim reporting periods for fiscal years beginning after December 15, 2019. Early adoption is permitted. The standard may be adopted either retrospectively or prospectively. The Company is currently assessing the future impact of this update on its consolidated financial statements and related disclosures. In August 2017, the FASB issued ASU No. 2017-12, Targeted Improvements to Accounting for Hedging Activities. This guidance eliminates the requirement to separately measure and report hedge ineffectiveness and generally requires, for qualifying hedges, the entire change in the fair value of a hedging instrument to be presented in the same income statement line as the hedged item. Additionally, the guidance also expands an entity's ability to apply hedge accounting for nonfinancial and financial risk components, simplifies the hedge documentation and hedge effectiveness assessment requirements, and modifies certain disclosure requirements. ASU 2017-12 is effective for reporting periods beginning after December 15, 2018, with early adoption permitted. The Company does not expect the adoption of this standard to have a material impact on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), to increase transparency and comparability of accounting for lease transactions. The new leasing standard requires lessees to recognize lease assets and lease liabilities on their balance sheet for all leases with a lease term of greater than 12 months. Lessor accounting is largely unchanged. Topic 842 is effective for fiscal years beginning after December 15, 2018, with early adoption permitted. In July 2018, the FASB provided an alternative transition method of adoption through ASU No. 2018-11, Targeted Improvements , which permits the recognition of a cumulative-effect adjustment to retained earnings on the date of adoption. The Company intends to adopt the standard beginning in fiscal 2020 using the modified retrospective transition approach, specifically, using the alternative transition method provided by ASU 2018-11. A dedicated implementation team has been established that continues to make progress toward completing the evaluation of the impact of the new standard. The Company's assessment efforts to date have included reviewing the provisions of Topic 842, gathering information to evaluate its lease population and portfolio, evaluating the nature of real and personal property and other arrangements that may meet the definition of a lease, designing and implementing one-time implementation controls as well as new post-adoption lease processes and controls, implementing a new lease accounting software solution, and evaluating certain accounting policy elections. The Company anticipates finalizing its accounting policy, accounting software, systems and process modifications during the fourth quarter of fiscal 2019. Based on a preliminary assessment, the Company does not expect there to be a significant change in determining what constitutes a lease, however, the Company expects that virtually all of its operating lease commitments will be subject to the new guidance and recognized as operating lease liabilities and right-of-use assets upon adoption, resulting in a significant increase in the assets and liabilities on its consolidated balance sheets. The pattern of recognition for operating leases within the consolidated statements of operations and comprehensive income is not anticipated to significantly change. The adoption is not expected to impact the Company’s ability to comply with financial covenants as defined within the Company's Sixth Amendment to its Credit Agreement dated July 23, 2018, as discussed further in Note 8, Debt. The Company is continuing to refine its process for quantifying the financial statement impacts and anticipates finalizing its assessment of the materiality of adopting Topic 842 in conjunction with reporting its results for the third quarter of fiscal 2019. In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, Disclosure Update and Simplification , amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders' equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders' equity presented in the balance sheet must be provided in a note or separate statement. The amendments set forth certain presentation requirements, including that such analysis should present a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed with all significant reconciling items described by appropriate captions with contributions from and distributions to owners shown separately. This final rule is effective 30 days after publication in the Federal Register and will generally be effective for the Company for the third quarter of fiscal year 2019. The Company does not expect the adoption of this standard to have a material impact on its consolidated financial statements. Other accounting and reporting pronouncements issued after September 30, 2018 and through the filing date are not expected to have a material impact on the Company's condensed consolidated financial statements.

Revenue

Revenue	6 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue	REVENUE Revenue Recognition The Company's revenues from contracts with customers (clients) are derived from offerings that include consulting, analytics, digital solutions, engineering, and cyber services, substantially with the U.S. government and its agencies and, to a lesser extent, subcontractors. The Company also serves foreign governments, as well as domestic and international commercial clients. The Company performs under various types of contracts, which include cost-reimbursable-plus-fee contracts, time-and-materials contracts, and fixed-price contracts. The Company considers a contract with a customer to exist under Topic 606 when there is approval and commitment from both the Company and the customer, the rights of the parties and payment terms are identified, the contract has commercial substance, and collectability of consideration is probable. The Company also will consider whether two or more contracts entered into with the same customer should be combined and accounted for as a single contract. Furthermore, in certain transactions with commercial clients and with the U.S. government, the Company may commence providing services prior to receiving a formal approval from the customer. In these situations, the Company will consider the factors noted above, the risks associated with commencing the work and legal enforceability in determining whether a contract with the customer exists under Topic 606. Customer contracts are often modified to change the scope, price, specifications or other terms within the existing arrangement. Contract modifications are evaluated by management to determine whether the modification should be accounted for as part of the original performance obligation(s) or as a separate contract. If the modification adds distinct goods or services and increases the contract value proportionate to the stand-alone selling price of the additional goods or services, it will be accounted for as a separate contract. Generally, the Company’s contract modifications do not include goods or services which are distinct, and therefore are accounted for as part of the original performance obligation(s) with any impact on transaction price or estimated costs at completion being recorded as through a cumulative catch-up adjustment to revenue. The Company evaluates each service deliverable contracted with the customer to determine whether they represent promises to transfer distinct goods or services. Under Topic 606, these are referred to as performance obligations. One or more service deliverables often represent a single performance obligation. This evaluation requires significant judgment and the impact of combining or separating performance obligations may change the time over which revenue from the contract is recognized. The Company’s contracts generally provide a set of integrated or highly interrelated tasks or services and are therefore accounted for as a single performance obligation. However, in cases where we provide more than one distinct good or service within a customer contract, the contract is separated into individual performance obligations which are accounted for discretely. Contracts with the U.S. government are subject to the Federal Acquisition Regulation ("FAR") and are priced based on estimated or actual costs of providing the goods or services. The Company derives a majority of its revenue from contracts awarded through a competitive bidding process. Pricing for non-U.S. government agencies and commercial customers is based on discrete negotiations with each customer. Certain of the Company’s contracts contain award fees, incentive fees or other provisions that may increase or decrease the transaction price. These variable amounts generally are awarded upon achievement of certain performance metrics, program milestones or cost targets and may be based upon customer discretion. Management estimates variable consideration as the most likely amount that we expect to achieve based on our assessment of the variable fee provisions within the contract, prior experience with similar contracts or clients, and management’s evaluation of the performance on such contracts. The Company may perform work under a contract that has not been fully funded if the work has been authorized by the management and the customer to proceed. The Company evaluates unfunded amounts as variable consideration in estimating the transaction price. We include the estimated variable consideration in our transaction price to the extent that it is probable that a significant reversal of revenue will not occur upon the ultimate settlement of the variable fee provision. In the limited number of situations where our contracts with customers contain more than one performance obligation, the Company allocates the transaction price of a contract between the performance obligations in the proportion to their respective stand-alone selling prices. The Company generally estimates the stand-alone selling price of performance obligations based on an expected cost-plus margin approach as allowed under Topic 606. Our U.S. government contracts generally contain FAR provisions that enable the customer to terminate a contract for default or for the convenience of the U.S. government. The Company recognizes revenue for each performance obligation identified within our customer contracts when, or as, the performance obligation is satisfied by transferring the promised goods or services. Revenue may either be recognized over time, or at a point in time. The Company generally recognizes revenue over time as our contracts typically involve a continuous transfer of control to the customer. A continuous transfer of control under contracts with the U.S. government and its agencies is evidenced by clauses which require the Company to be paid for costs incurred plus a reasonable margin in the event that the customer unilaterally terminates the contract for convenience. For contracts where the Company recognizes revenue over time, a contract cost-based input method is generally used to measure progress towards satisfaction of the underlying performance obligation(s). Contract costs include direct costs such as materials, labor and subcontract costs, as well as indirect costs identifiable with, or allocable to, a specific contract that are expensed as incurred. The Company does not incur material incremental costs to acquire or fulfill contracts. Under a contract cost-based input method, revenue is recognized based on the proportion of contract costs incurred to the total estimated costs expected to be incurred upon completion of the underlying performance obligation. The Company includes both funded and unfunded portions of customer contracts in this estimation process. For interim financial reporting periods, contract revenue attributable to indirect costs is recognized based upon agreed-upon annual forward-pricing rates established with the U.S. government at the start of each fiscal year. Forward pricing rates are estimated and agreed upon between the Company and the U.S. government and represent indirect contract costs required to execute and administer contract obligations. The impact of any agreed-upon changes, or changes in the estimated annual forward-pricing rates, will be recorded in the interim financial reporting period when such changes are identified. This change relates to the interim financial reporting period differences between the actual indirect cost incurred and allocated to customer contracts compared to the estimated amounts allocated to contracts using the estimated annual forward-pricing rates established with the U.S. government. On certain contracts, principally time-and-materials and cost-reimbursable-plus-fee contracts, revenue is recognized using the right-to-invoice practical expedient as the Company is contractually able to invoice the customer based on the control transferred. However, we did not elect to use the practical expedient which would allow the Company to exclude contracts recognized using the right-to-invoice practical expedient from the remaining performance obligations disclosed below. Additionally, for stand-ready performance obligations to provide services under fixed-price contracts, revenue is recognized over time using a straight-line measure of progress as the control of the services is provided to the customer ratably over the term of the contract. If a contract does not meet the criteria for recognition of revenue over time, we recognize revenue at the point in time when control of the good or service is transferred to the customer. Determining a measure of progress towards the satisfaction of performance obligations requires management to make judgments that may affect the timing of revenue recognition. In addition to the right-to-invoice practical expedient discussed above, the Company applied certain other practical expedients permitted by Topic 606, which include: a) using the portfolio approach where contracts with similar characteristics were assessed collectively to evaluate risk of being impacted by the adoption of Topic 606; b) applying the practical expedient allowing the Company to not restate completed contracts which began and ended in the same fiscal year prior to the date of the initial adoption; and c) electing to omit the disclosure related to remaining performance obligations for reporting periods presented before the date of the initial adoption. Contract Estimates Many of our contracts recognize revenue under a contract cost-based input method and require an Estimate-at-Completion (EAC) process, which management uses to review and monitor the progress towards the completion of our performance obligations. Under this process, management considers various inputs and assumptions related to the EAC, including, but not limited to, progress towards completion, labor costs and productivity, material and subcontractor costs, and identified risks. Estimating the total cost at completion of performance obligations is subjective and requires management to make assumptions about future activity and cost drivers under the contract. Changes in these estimates can occur for a variety of reasons and, if significant, may impact the profitability of the Company’s contracts. Changes in estimates related to contracts accounted for under the EAC process are recognized in the period when such changes are made on a cumulative catch-up basis. If the estimate of contract profitability indicates an anticipated loss on a contract, the Company recognizes the total loss at the time it is identified. For the three and six months periods ended September 30, 2018 and 2017 , respectively, the aggregate impact of adjustments in contract estimates was not material. Performance Obligations Remaining performance obligations represent the transaction price of exercised contracts for which work has not yet been performed, irrespective of whether funding has or has not been authorized and appropriated as of the date of exercise. Remaining performance obligations do not include negotiated but unexercised options. As of September 30, 2018 , the Company had $7.8 billion of remaining performance obligations and we expect to recognize more than half of the remaining performance obligations as revenue over the next 12 months, and approximately three quarters over the next 24 months. The remainder is expected to be recognized thereafter. Disaggregation of Revenue We disaggregate our revenue from contracts with customers by contract type, customer, as well as whether the Company acts as prime contractor or sub-contractor, as we believe these categories best depict how the nature, amount, timing and uncertainty of our revenue and cash flows are affected by economic factors. The following series of tables presents our revenue disaggregated by these categories. Revenue by Contract Type: We generate revenue under the following three basic types of contracts: • Cost-Reimbursable Contracts: Cost-reimbursable contracts provide for the payment of allowable costs incurred during performance of the contract, up to a ceiling based on the amount that has been funded, plus a fixed fee or award fee. • Time-and-Materials Contracts: Under contracts in this category, we are paid a fixed hourly rate for each direct labor hour expended, and we are reimbursed for billable material costs and billable out-of-pocket expenses inclusive of allocable indirect costs. We assume the financial risk on time-and-materials contracts because our costs of performance may exceed negotiated hourly rates. • Fixed-Price Contracts: Under a fixed-price contract, we agree to perform the specified work for a predetermined price. To the extent our actual direct and allocated indirect costs decrease or increase from the estimates upon which the price was negotiated, we will generate more or less profit, respectively, or could incur a loss. The table below presents the total revenue for each type of contract: Three Months Ended Six Months Ended 2018 2017 2018 2017 Cost-reimbursable $ 851,394 53 % $ 795,819 52 % $ 1,711,278 53 % $ 1,565,914 51 % Time-and-materials 390,509 24 % 384,587 25 % 796,093 24 % 766,814 25 % Fixed-price 372,094 23 % 362,399 23 % 753,474 23 % 733,087 24 % Total Revenue $ 1,613,997 100 % $ 1,542,805 100 % $ 3,260,845 100 % $ 3,065,815 100 % Revenue by Customer Type: Three Months Ended Six Months Ended 2018 2017 2018 2017 U.S. government: Defense Clients $ 755,570 47 % $ 706,526 46 % $ 1,513,552 47 % $ 1,418,265 46 % Intelligence Clients 385,733 24 % 379,536 25 % 783,213 24 % 748,005 24 % Civil Clients 417,636 26 % 403,410 26 % 853,162 26 % 808,694 27 % Total U.S. government 1,558,939 97 % 1,489,472 97 % 3,149,927 97 % 2,974,964 97 % Global Commercial Clients 55,058 3 % 53,333 3 % 110,918 3 % 90,851 3 % Total Revenue $ 1,613,997 100 % $ 1,542,805 100 % $ 3,260,845 100 % $ 3,065,815 100 % Revenue by Whether the Company Acts as a Prime Contractor or a Sub-Contractor: Three Months Ended Six Months Ended 2018 2017 2018 2017 Prime Contractor $ 1,482,153 92 % $ 1,413,210 92 % $ 2,989,335 92 % $ 2,801,249 91 % Sub-contractor 131,844 8 % 129,595 8 % 271,510 8 % 264,566 9 % Total Revenue $ 1,613,997 100 % $ 1,542,805 100 % $ 3,260,845 100 % $ 3,065,815 100 % Contract Balances Contract assets primarily consist of unbilled receivables typically resulting from revenue recognized exceeding the amount billed to the customer and right to payment is not just subject to the passage of time. Contract liabilities primarily consist of advance payments, billings in excess of costs incurred and deferred revenue. Contract assets and liabilities are reported on a net contract basis at the end of each reporting period. The Company maintains an allowance for doubtful accounts to provide for an estimate of uncollected receivables. Refer to Note 5 for more information on receivables recognized from contracts accounted for under Topic 606. The following table summarizes the contract balances recognized on the Company’s condensed consolidated balance sheets: September 30, March 31, Contract assets: Current $ 749,672 $ 738,646 Long-term 60,093 59,633 Total $ 809,765 $ 798,279 Contract liabilities: Advance payments, billings in excess of costs incurred and deferred revenue $ 22,165 $ 27,522 Changes in contract assets and contract liabilities are primarily due to the timing difference between the Company’s performance of services and payments from customers. For the three months ended September 30, 2018 and 2017 , we recognized revenue of $ 3.8 million and $ 0.8 million and for the six months ended September 30, 2018 and 2017 , we recognized revenue of $ 10.6 million and $ 6.6 million related to our contract liabilities on April 1, 2018 and 2017, respectively. To determine revenue recognized from contract liabilities during the reporting periods, the Company allocates revenue to individual contract liability balances and applies revenue recognized during the reporting periods first to the beginning balances of contract liabilities until the revenue exceeds the balances.

Earnings Per Share

Earnings Per Share	6 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE The Company computes basic and diluted earnings per share amounts based on net income for the periods presented. The Company uses the weighted-average number of common shares outstanding during the period to calculate basic earnings per share, or EPS. Diluted EPS adjusts the weighted average number of shares outstanding to include the dilutive effect of outstanding common stock options and other stock-based awards. The Company currently has outstanding shares of Class A Common Stock. Unvested Class A Restricted Common Stock holders are entitled to participate in non-forfeitable dividends or other distributions. These unvested restricted shares participated in the Company's dividends declared and were paid in the first and second quarters of fiscal 2019 and 2018 . As such, EPS is calculated using the two-class method whereby earnings are reduced by distributed earnings as well as any available undistributed earnings allocable to holders of unvested restricted shares. A reconciliation of the income used to compute basic and diluted EPS for the periods presented are as follows: Three Months Ended Six Months Ended 2018 2017 2018 2017 Earnings for basic computations (1) $ 92,127 $ 72,966 $ 195,681 $ 142,974 Weighted-average common shares outstanding for basic computations 142,443,058 147,085,314 142,861,491 147,400,153 Earnings for diluted computations (1) $ 92,130 $ 72,971 $ 195,690 $ 142,986 Dilutive stock options and restricted stock 1,265,851 1,802,183 1,353,582 1,976,722 Weighted-average common shares outstanding for diluted computations 143,708,909 148,887,497 144,215,073 149,376,875 Earnings per common share Basic $ 0.65 $ 0.50 $ 1.37 $ 0.97 Diluted $ 0.64 $ 0.49 $ 1.36 $ 0.96 (1) During the three months ended September 30, 2018 and 2017 , approximately 0.9 million and 1.4 million participating securities, respectively, were paid dividends totaling $0.2 million in both periods. During the six months ended September 30, 2018 and 2017 , approximately 0.9 million and 1.4 million participating securities, respectively, were paid dividends totaling $0.3 million and $0.4 million , respectively. For the three months ended September 30, 2018 and 2017 , there were undistributed earnings of $0.4 million and $0.4 million , respectively, allocated to the participating class of securities in both basic and diluted EPS. For the six months ended September 30, 2018 and 2017 , there were undistributed earnings of $0.9 million and $0.9 million , respectively, allocated to the participating class of securities in both basic and diluted EPS. The allocated undistributed earnings and the dividends paid comprise the difference between net income presented on the condensed consolidated statements of operations and earnings for basic and diluted computations for the three and six months ended September 30, 2018 and 2017 . The EPS calculation for the three months ended September 30, 2018 and 2017 excludes 0.2 million and 0.4 million options, respectively, as their impact was anti-dilutive. The EPS calculation for the six months ended September 30, 2018 and 2017 excludes 0.2 million and 0.3 million options, respectively, as their impact was anti-dilutive.

Accounts Receivable, Net of All

Accounts Receivable, Net of Allowance	6 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Accounts Receivable, Net of Allowance	ACCOUNTS RECEIVABLE, NET OF ALLOWANCE Accounts receivable, net of allowance consisted of the following: September 30, March 31, Current assets Accounts receivable–billed $ 416,909 $ 395,136 Accounts receivable–unbilled 749,672 738,646 Allowance for doubtful accounts (1,255 ) (77 ) Accounts receivable, net of allowance 1,165,326 1,133,705 Other long-term assets Accounts receivable–unbilled 60,093 59,633 Total accounts receivable, net $ 1,225,419 $ 1,193,338 Unbilled amounts represent revenues for which billings have not been presented to customers at quarter-end or year-end. These amounts are usually billed and collected within one year. Long-term unbilled receivables not anticipated to be billed and collected within one year, which are primarily related to retainage, holdbacks, and long-term rate settlements to be billed at contract closeout, are included in other long-term assets in the accompanying condensed consolidated balance sheets. The Company recognized a provision for doubtful accounts (including certain unbilled reserves) of $10.6 million and $2.2 million for the three months ended September 30, 2018 and 2017 , respectively and $10.7 million and $3.1 million for the six months ended September 30, 2018 and 2017 . The primary financial instruments, other than derivatives, that potentially subject the Company to concentrations of credit risk are accounts receivable. The Company's primary customers are U.S. federal government agencies and prime contractors under contracts with the U.S. government. The Company continuously reviews its accounts receivable and records provisions for doubtful accounts as needed.

Accounts Payable and Other Accr

Accounts Payable and Other Accrued Expenses	6 Months Ended
	Sep. 30, 2018
Payables and Accruals [Abstract]
Accounts Payable and Other Accrued Expenses	ACCOUNTS PAYABLE AND OTHER ACCRUED EXPENSES Accounts payable and other accrued expenses consisted of the following: September 30, March 31, Vendor payables $ 377,245 $ 339,993 Accrued expenses 261,017 217,566 Total accounts payable and other accrued expenses $ 638,262 $ 557,559 Accrued expenses consisted primarily of the Company’s reserve related to potential cost disallowance in conjunction with government audits. Refer to Note 18 for further discussion of this reserve.

Accrued Compensation and Benefi

Accrued Compensation and Benefits	6 Months Ended
	Sep. 30, 2018
Compensation Related Costs [Abstract]
Accrued Compensation and Benefits	ACCRUED COMPENSATION AND BENEFITS Accrued compensation and benefits consisted of the following: September 30, March 31, Bonus $ 44,105 $ 87,817 Retirement 66,411 35,743 Vacation 135,233 131,519 Other 26,212 27,671 Total accrued compensation and benefits $ 271,961 $ 282,750

Debt

Debt	6 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Debt	DEBT Debt consisted of the following: September 30, 2018 March 31, 2018 Interest Rate Outstanding Balance Interest Rate Outstanding Balance Term Loan A 3.74 % $ 1,064,700 3.88 % $ 1,094,275 Term Loan B 4.24 % 393,025 3.88 % 395,000 Senior Notes 5.13 % 350,000 5.13 % 350,000 Less: Unamortized debt issuance costs and discount on debt (20,926 ) (20,696 ) Total 1,786,799 1,818,579 Less: Current portion of long-term debt (63,100 ) (63,100 ) Long-term debt, net of current portion $ 1,723,699 $ 1,755,479 Term Loans and Revolving Credit Facility On July 23, 2018 (the "Amendment Effective Date"), Booz Allen Hamilton Inc. ("Booz Allen Hamilton") and Booz Allen Hamilton Investor Corporation ("Investor"), and certain wholly-owned subsidiaries of Booz Allen Hamilton, entered into the Sixth Amendment (the "Sixth Amendment") to the Credit Agreement (as amended, the "Credit Agreement"), dated as of July 31, 2012 among Booz Allen Hamilton, Investor, certain wholly-owned subsidiaries of Booz Allen Hamilton and Bank of America, N.A., as Administrative Agent, and Collateral Agent and the other lenders and financial institutions from time to time party thereto (as previously amended by the First Amendment to the Credit Agreement, dated as of August 16, 2013, the Second Amendment to Credit Agreement, dated as of May 7, 2014, the Third Amendment to the Credit Agreement, dated as of July 13, 2016, the Fourth Amendment to the Credit Agreement, dated as of February 6, 2017, and the Fifth Amendment to the Credit Agreement, dated as of March 7, 2018). The Sixth Amendment provides for a new delayed draw (the "Delayed Draw Facility") on the tranche A term loan ("Term Loan A") facility in the amount of up to $400.0 million and extended the maturity of the Term Loan A and the revolving credit facility (the "Revolving Credit Facility") to July 2023. Additionally, the Sixth Amendment reduced the interest rate spread applicable to the Term Loan A and the Revolving Credit Facility from a range of 1.50% to 2.25% to a range of 1.25% to 2.00% based on consolidated net total leverage. The interest rate applicable to the Term Loan B ("Term Loan B" and, together with Term Loan A, the "Term Loans") remained unchanged. Prior to the Sixth Amendment, approximately $1,079.5 million was outstanding under Term Loan A. Pursuant to the Sixth Amendment, certain lenders converted their existing Term Loan A loans into a new tranche of Term Loan A loans in an aggregate amount, along with Term Loan A loans advanced by certain new lenders, of approximately $1,479.5 million , $400.0 million of which will be available as the Delayed Draw Facility. The Delayed Draw Facility is accessible for nine months from the Amendment Effective Date (the "Delayed Draw Availability Period"). The Company is able to draw on the Delayed Draw Facility on up to two occasions during the Delayed Draw Availability Period in an amount per draw (x) of not less than $100.0 million per draw or (y) equal to the amount of unused commitments in respect of the Delayed Draw Facility remaining at the time of such borrowing. The proceeds from the new lenders were used to prepay in full all of the existing Term Loan A that was not converted into the new Term Loan A tranche. The proceeds of the Delayed Draw Facility will be used for general corporate purposes and other purposes not prohibited by the Credit Agreement. Prior to the Sixth Amendment, $500.0 million was available under the revolving credit facility. Pursuant to the Sixth Amendment, certain lenders under the Existing Credit Agreement converted their Existing Revolving Commitments into a new tranche of revolving commitments (the "New Revolving Commitments" and the revolving credit loans made thereunder, the "New Revolving Loans") in an aggregate amount, along with New Revolving Commitments of certain new lenders, of $500.0 million . As of September 30, 2018 , the Credit Agreement provided Booz Allen Hamilton with a $1,064.7 million Term Loan A, $400.0 million Delayed Draw Facility, a $393.0 million Term Loan B, and $500.0 million in New Revolving Commitments with a sub-limit for letters of credit of $100.0 million . As of September 30, 2018 , the maturity date of Term Loan A and the termination date for the Revolving Credit Facility was July 23, 2023 and the maturity date of Term Loan B was June 30, 2023. Booz Allen Hamilton’s obligations and the guarantors’ guarantees under the Credit Agreement are secured by a first priority lien on substantially all of the assets (including capital stock of subsidiaries) of Booz Allen Hamilton, Investor, and the subsidiary guarantors, subject to certain exceptions set forth in the Credit Agreement and related documentation. Subject to specified conditions, without the consent of the then-existing lenders (but subject to the receipt of commitments), the Term Loans or New Revolving Credit Facility may be expanded (or a new term loan facility or revolving credit facility added to the existing facilities) by up to (i) greater of (x) $627 million and (y) 100% of consolidated EBITDA of Booz Allen Hamilton, as of the end of the most recently ended four quarter period for which financial statements have been delivered pursuant to the Credit Agreement plus (ii) the aggregate principal amount under which pro forma consolidated net secured leverage remains less than or equal to 3.50 : 1.00 . At Booz Allen Hamilton’s option, borrowings under the Secured Credit Facility bear interest based either on LIBOR (adjusted for maximum reserves, and subject to a floor of zero ) for the applicable interest period or a base rate (equal to the highest of (x) the administrative agent’s prime corporate rate, (y) the overnight federal funds rate plus 0.50% , and (z) three-month LIBOR (adjusted for maximum reserves, and subject to a floor of zero ) plus 1.00% ), in each case plus an applicable margin, payable at the end of the applicable interest period and in any event at least quarterly. The applicable margin for Term Loan A and borrowings under the Revolving Credit Facility ranges from 1.25% to 2.00% for LIBOR loans and 0.25% to 1.00% for base rate loans, in each case based on Booz Allen Hamilton’s consolidated total net leverage ratio. The applicable margin for Term Loan B is 2.00% for LIBOR loans and 1.00% for base rate loans. Unused commitments under the Revolving Credit Facility are subject to a quarterly fee ranging from 0.20% to 0.35% based on Booz Allen Hamilton’s consolidated total net leverage ratio. Booz Allen Hamilton occasionally borrows under the Revolving Credit Facility in anticipation of cash demands. During the first and second quarters of fiscal 2019 , Booz Allen Hamilton accessed a total of $70.0 million of the $500.0 million New Revolving Commitments. As of September 30, 2018 and March 31, 2018 , there were no amounts outstanding under the Revolving Credit Facility. The Credit Agreement requires quarterly principal payments of 1.25% of the stated principal amount of Term Loan A until maturity, and quarterly principal payments of 0.25% of the stated principal amount of Term Loan B until maturity. The Credit Agreement contains customary representations and warranties and customary affirmative and negative covenants. The negative covenants include limitations on the following, in each case subject to certain exceptions: (i) indebtedness and liens, (ii) mergers, consolidations or amalgamations, liquidations, wind-ups or dissolutions, and disposition of all or substantially all assets; (iii) dispositions of property; (iv) restricted payments; (v) investments; (vi) transactions with affiliates; (vii) change in fiscal periods; (viii) negative pledges; (ix) restrictive agreements; (x) line of business; and (xi) speculative hedging. The events of default include the following, in each case subject to certain exceptions: (a) failure to make required payments under the Secured Credit Facility; (b) material breaches of representations or warranties under the Secured Credit Facility; (c) failure to observe covenants or agreements under the Secured Credit Facility; (d) failure to pay or default under certain other material indebtedness; (e) bankruptcy or insolvency; (f) certain Employee Retirement Income Security Act, or ERISA events; (g) certain material judgments; (h) actual or asserted invalidity of the Guarantee and Collateral Agreements or the other security documents or failure of the guarantees or perfected liens thereunder; and (i) a change of control. In addition, Booz Allen Hamilton is required to meet certain financial covenants at each quarter end, namely Consolidated Net Total Leverage and Consolidated Net Interest Coverage Ratios. As of September 30, 2018 and March 31, 2018 , Booz Allen Hamilton was in compliance with all financial covenants associated with its debt and debt-like instruments. Senior Notes On April 25, 2017, Booz Allen Hamilton issued $350 million aggregate principal amount of its 5.125% Senior Notes (the "Senior Notes"), under an Indenture, dated as of April 25, 2017, among Booz Allen Hamilton, certain subsidiaries of Booz Allen Hamilton, as guarantors (the "Subsidiary Guarantors"), and Wilmington Trust, National Association, as trustee (the "Trustee"), as supplemented by the First Supplemental Indenture, dated as of April 25, 2017, among Booz Allen Hamilton, the Subsidiary Guarantors and the Trustee. Each of Booz Allen Hamilton's existing and future domestic restricted subsidiaries that guarantee its obligations under the Secured Credit Facility and certain other indebtedness will guarantee the Senior Notes on a senior unsecured basis. Interest is payable semi-annually on May 1 and November 1 of each year, beginning on November 1, 2017, and principal is due at maturity on May 1, 2025. In connection with the Senior Notes, the Company recognized $6.7 million of issuance costs, which were recorded as an offset against the carrying value of debt and will be amortized to interest expense over the term of the Senior Notes. During the first and second quarters of fiscal 2019, interest payments of $9.0 million were made for the Senior Notes. Borrowings under the Term Loans and, if used, the Revolving Credit Facility, incur interest at a variable rate. In accordance with Booz Allen Hamilton’s risk management strategy, between April 6, 2017 and May 24, 2017, Booz Allen Hamilton executed a series of interest rate swaps. As of September 30, 2018 , Booz Allen Hamilton had interest rate swaps with an aggregate notional amount of $450 million . These instruments hedge the variability of cash outflows for interest payments on the floating portion of the term loan debt. The Company's objectives in using cash flow hedges are to reduce volatility due to interest rate movements and to add stability to interest expense (See Note 9 in our condensed consolidated financial statements). Interest on debt and debt-like instruments consisted of the following: Three Months Ended Six Months Ended 2018 2017 2018 2017 (In thousands) (In thousands) Term Loan A Interest Expense $ 10,345 $ 9,394 $ 21,187 $ 18,171 Term Loan B Interest Expense 4,115 3,518 8,032 6,791 Interest on Revolving Credit Facility 2 199 61 199 Senior Notes Interest Expense 4,485 4,484 8,969 7,773 Deferred Payment Obligation Interest (1) 1,993 2,011 4,015 4,022 Amortization of Debt Issuance Cost (DIC) and Original Issue Discount (OID) (2) 1,258 1,343 2,618 2,633 Other 49 9 439 116 Total Interest Expense $ 22,247 $ 20,958 $ 45,321 $ 39,705 (1) Interest payments on the deferred payment obligation are made twice a year in January and July. (2) DIC and OID on the Term Loans and Senior Notes are recorded as a reduction of long-term debt in the condensed consolidated balance sheet and are amortized ratably over the life of the related debt using the effective rate method. DIC on the Revolving Credit Facility is recorded as a long-term asset on the condensed consolidated balance sheet and amortized ratably over the term of the Revolving Credit Facility.

Derivatives

Derivatives	6 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	DERIVATIVES The Company utilizes derivative financial instruments to manage interest rate risk related to its variable rate debt. The Company’s objectives in using these interest rate derivatives, which were designated as cash flow hedges, are to manage its exposure to interest rate movements and reduce volatility to interest expense. During the first quarter of fiscal 2018, the Company entered into several forward starting floating-to-fixed interest rate swap agreements with multiple financial institutions with a start date of April 30, 2018. The aggregate notional amount of these interest rate swap agreements was $450 million as of September 30, 2018 . The swaps have staggered maturities, ranging from June 30, 2021 to June 30, 2022. These swaps mature within the last tranche of the Company's floating rate debt (June 30, 2023). The floating-to-fixed interest rate swaps involve the exchange of variable interest amounts from a counterparty for the Company making fixed-rate interest payments over the life of the agreements without exchange of the underlying notional amount and effectively converting a portion of the variable rate debt into fixed interest rate debt. Derivative instruments are recorded in the condensed consolidated balance sheet on a gross basis at estimated fair value. As of September 30, 2018 , $2.8 million and $9.1 million were classified as other current assets and other long-term assets, respectively, on the condensed consolidated balance sheet. As of March 31, 2018 , $0.7 million and $7.2 million were classified as other current assets and other long-term assets, respectively, on the condensed consolidated balance sheet. For interest rate swaps designated as cash flow hedges, the changes in the fair value of derivatives is recorded in Accumulated Other Comprehensive Income, or AOCI, net of taxes, and is subsequently reclassified into interest expense in the period that the hedged forecasted interest payments are made on the Company's variable-rate debt. For the three and six months ended September 30, 2018 , a $1.2 million and $3.0 million gain, respectively, was recognized in AOCI, and $0.1 million and $0.08 million was reclassified into interest expense. For the three and six months ended September 30, 2017 , a $0.1 million and $0.6 million loss was recognized in AOCI, and there were no amounts reclassified into interest expense. The ineffective portion of the change in fair value of the derivatives is recognized directly in earnings. As of September 30, 2018 , there was no ineffectiveness recognized in earnings. Over the next 12 months, the Company estimates that $2.8 million will be reclassified as a decrease to interest expense. Cash flows associated with periodic settlements of interest rate swaps will be classified as operating activities in the condensed consolidated statement of cash flows. The Company is subject to counterparty risk in connection with its interest rate swap derivative contracts. Credit risk related to a derivative financial instrument represents the possibility that the counterparty will not fulfill the terms of the contract. The Company mitigates this credit risk by entering into agreements with credit-worthy counterparties and regularly reviews its credit exposure and the creditworthiness of the counterparties.

Income Taxes

Income Taxes	6 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES The 2017 Tax Act was enacted on December 22, 2017. The 2017 Tax Act reduced the U.S. federal corporate tax rate from 35.0% to 21.0% effective January 1, 2018. At September 30, 2018 , the Company's assessment for the following elements was not complete: (1) the acceleration of depreciation; and (2) the limitation on the deductibility of certain executive compensation. However, based on a preliminary assessment of the recently issued IRS Notice 2018-68, the Company recognized an additional measurement-period adjustment of $1.1 million relating to the deductibility of certain executive compensation, with a corresponding adjustment of $1.1 million to income tax expense during the quarter. The effect of the measurement-period adjustment on the three months ended September 30, 2018 effective tax rate was approximately 0.9% . The Company will continue to make and refine the calculations as additional analysis is completed and our estimates may be materially affected by additional clarifications and interpretations of the legislation. This includes the written consent the Company received from the IRS on October 19, 2018 in response to its application for a Change in Accounting Method filed on March 29, 2018. This method change is related to the Company’s recognition of revenue for income tax purposes associated with its unbilled receivables. Since this consent agreement was received subsequent to September 30, 2018, the financial statement effect related to a measurement-period adjustment of these changes will be recorded in the Company’s third quarter of fiscal 2019 pursuant to ASC 740. The Company will incorporate this method change in its fiscal 2018 federal and state income tax returns. As of September 30, 2018, the Company preliminarily estimates the measurement-period adjustment impact to fiscal 2019 from this method change to be approximately $28.9 million of a reduction to income tax expense.The Company expects to finalize its assessment of all provisional amounts within the allowed one-year measurement period provided for under SAB 118. Other than the executive compensation discussed above, the Company has not made any additional adjustments to fiscal 2018 provisional amounts during the six months ended September 30, 2018 . The Company’s effective income tax rates were 22.7% and 33.4% for the three months ended September 30, 2018 and 2017 , respectively, and 23.5% and 33.6% for the six months ended September 30, 2018 and 2017 , respectively. The decrease in the effective tax rate as compared to the same period last fiscal year was primarily due to the 2017 Tax Act's reduction of the U.S. federal corporate tax rate. The effective tax rates of 22.7% and 23.5% for the three and six months ended September 30, 2018 differ from the federal statutory rate of 21.0% primarily due to the inclusion of state income taxes and permanent rate differences, which are predominantly related to meals and entertainment and certain executive compensation, offset in the current three months by discrete tax items. The Company is currently contesting tax assessments from the District of Columbia Office of Tax and Revenue for fiscal years 2013 through 2015 at various stages of applicable administrative and judicial processes, with a combined amount at issue of approximately $11.5 million , net of associated tax benefits as of September 30, 2018. The Company has taken similar tax positions with respect to subsequent fiscal years, totaling in aggregate $28.3 million . As of September 30, 2018 , the Company does not maintain reserves for any uncertain tax positions related to the contested tax benefits, and, given the recoverable nature of the state tax expense, it does not believe the resolution of these matters will have a material adverse effect on its results of operations, cash flows or financial condition. The Company continues to carry a reserve of $10.2 million for income tax uncertainties created with the business acquisition of eGov Holdings, Inc. (d/b/a Aquilent) in the fourth quarter of fiscal 2017 resulting from uncertainty in the sustainability of the acquiree's prior tax-return positions under examination with the relevant tax authorities.

Other Long-Term Liabilities

Other Long-Term Liabilities	6 Months Ended
	Sep. 30, 2018
Other Liabilities Disclosure [Abstract]
Other Long-Term Liabilities	OTHER LONG-TERM LIABILITIES Other long-term liabilities consisted of the following: September 30, March 31, Deferred rent $ 77,323 $ 79,913 Postretirement benefit obligations 135,191 131,526 Other (1) 48,035 48,443 Total other long-term liabilities $ 260,549 $ 259,882 (1) Balances at September 30, 2018 and March 31, 2018 include the Company's long-term disability obligation of $22.8 million for both periods as well as contingent consideration related to the Company's business acquisition of an acquiree in the fourth quarter of fiscal 2017 of $3.3 million and $3.6 million , respectively.

Employee Benefit Plans

Employee Benefit Plans	6 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS Defined Contribution Plan The Company sponsors the Employees’ Capital Accumulation Plan, or ECAP, which is a qualified defined contribution plan that covers eligible U.S. and international employees. ECAP provides for distributions, subject to certain vesting provisions, to participants by reason of retirement, death, disability, or termination of employment. Effective April 1, 2014, the Company transitioned from a discretionary employer contribution to an annual matching contribution of up to 6% of eligible annual income as determined by the Internal Revenue Code for the ECAP. Total expense recognized under ECAP was $33.6 million and $30.7 million for the three months ended September 30, 2018 and 2017 , respectively, and $66.2 million and $61.8 million for the six months ended September 30, 2018 and 2017 , respectively. The Company-paid contributions were $16.9 million and $15.5 million for the three months ended September 30, 2018 and 2017 , respectively, and $34.4 million and $31.1 million for the six months ended September 30, 2018 and 2017 , respectively. Defined Benefit Plan and Other Postretirement Benefit Plans The Company provides postretirement healthcare benefits to former officers under a medical indemnity insurance plan, with premiums paid by the Company. This plan is referred to as the Officer Medical Plan. The Company also established a non-qualified defined benefit plan for all officers in May 1995, or the Retired Officers' Bonus Plan, which pays a lump-sum amount of $10,000 per year of service as an officer, provided the officer meets retirement vesting requirements. In addition, the Company provides a fixed annual allowance after retirement to cover financial counseling and other expenses. The Retired Officers' Bonus Plan is not salary related, but rather is based primarily on years of service. During fiscal 2017, the Company adopted a new plan which will provide for a one-time, lump sum retirement payment of one month’s salary when a vice-president retires from the Company, effective April 1, 2017. This is referred to as the Retired Vice-President Bonus Plan. Additionally, the Company offers medical and dental benefits to inactive employees (and their eligible dependents) on long-term disability. The components of net postretirement medical expense for the Officer Medical Plan were as follows: Three Months Ended Six Months Ended 2018 2017 2018 2017 Service cost $ 1,488 $ 1,116 $ 2,976 $ 2,232 Interest cost 1,282 1,252 2,564 2,504 Net actuarial loss 527 568 1,054 1,135 Total postretirement medical expense $ 3,297 $ 2,936 $ 6,594 $ 5,871 The service cost component of net periodic benefit cost is included in cost of revenue and general and administrative expenses, and the non-service cost components of net periodic benefit cost (interest cost and net actuarial loss) is included as part of other income (expense), net in the accompanying condensed consolidated statements of operations. As of September 30, 2018 and March 31, 2018 , the unfunded status of the post-retirement medical plan was $130.5 million and $126.9 million , respectively, which is included in other long-term liabilities in the accompanying condensed consolidated balance sheets. Deferred Compensation Plan The Company established a non-qualified deferred compensation plan (the "Plan") for certain executives and other highly compensated employees that became effective in the current period. Pursuant to the Plan, participants are eligible to defer up to 100% of their incentive cash compensation on a tax deferred basis in excess of the IRS limits imposed on 401(k) plans. The assets of the plan are held in a consolidated trust and are subject to the claims of the Company's general creditors under federal and state laws in the event of insolvency. Consequently, the trust qualifies as a Rabbi trust for income tax purposes. As of September 30, 2018 , $3.2 million of plan investments and obligations were recorded in other long term assets and in other long term liabilities, respectively, in the condensed consolidated balance sheets, representing the fair value related to the deferred compensation plan. Adjustments to the fair value of the plan investments and obligations are recorded in operating expenses.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	6 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Accumulated Other Comprehensive Loss	ACCUMULATED OTHER COMPREHENSIVE LOSS All amounts recorded in other comprehensive loss are related to the Company's post-retirement plans and interest rate swaps designated as cash flow hedges. The following table shows the changes in accumulated other comprehensive income (loss), net of tax: Three Months Ended September 30, 2018 Six Months Ended September 30, 2018 Post-retirement plans Derivatives designated as cash flow hedges Totals Post-retirement plans Derivatives designated as cash flow hedges Totals Beginning of period $ (20,548 ) $ 7,769 $ (12,779 ) $ (20,955 ) $ 5,849 $ (15,106 ) Other comprehensive income (loss) before reclassifications (1) — 1,154 1,154 — 3,041 3,041 Amounts reclassified from accumulated other comprehensive loss 424 (116 ) 308 831 (83 ) 748 Net current-period other comprehensive income (loss) 424 1,038 1,462 831 2,958 3,789 End of period $ (20,124 ) $ 8,807 $ (11,317 ) $ (20,124 ) $ 8,807 $ (11,317 ) (1) Changes in other comprehensive income (loss) before reclassification for derivatives designated as cash flow hedges are recorded net of tax expenses of $0.4 million and $1.1 million for the three and six months ended September 30, 2018 , respectively. Three Months Ended September 30, 2017 Six Months Ended September 30, 2017 Post-retirement plans Derivatives designated as cash flow hedges Totals Post-retirement plans Derivatives designated as cash flow hedges Totals Beginning of period $ (16,714 ) $ (510 ) $ (17,224 ) $ (17,077 ) $ — $ (17,077 ) Other comprehensive income (loss) before reclassifications (2) — (124 ) (124 ) — (634 ) (634 ) Amounts reclassified from accumulated other comprehensive loss 361 — 361 724 — 724 Net current-period other comprehensive income (loss) 361 (124 ) 237 724 (634 ) 90 End of period $ (16,353 ) $ (634 ) $ (16,987 ) $ (16,353 ) $ (634 ) $ (16,987 ) (2) Changes in other comprehensive income (loss) before reclassification for derivatives designated as cash flow hedges are recorded net of tax benefits of $0.1 million and $0.4 million for the three and six months ended September 30, 2017 , respectively. The following table presents the reclassifications out of accumulated other comprehensive loss to net income: Three Months Ended Six Months Ended 2018 2017 2018 2017 Amounts reclassified from accumulated other comprehensive loss: Post-retirement plans (Note 12): Amortization of net actuarial loss included in net periodic benefit cost $ 551 $ 596 $ 1,101 $ 1,193 Tax benefit (expense) (127 ) (235 ) (270 ) (469 ) Net of tax $ 424 $ 361 $ 831 $ 724

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Stockholders' Equity	STOCKHOLDERS’ EQUITY Common Stock The common stock shares activity consisted of the following: Class A Common Stock Treasury Stock Balance at March 31, 2017 155,901,485 7,013,777 Issuance of common stock 866,099 — Stock options exercised 1,261,089 — Repurchase of common stock (1) — 7,568,357 Balance at March 31, 2018 158,028,673 14,582,134 Issuance of common stock 417,366 — Stock options exercised 678,173 — Repurchase of common stock (2) — 1,991,299 Balance at September 30, 2018 159,124,212 16,573,433 (1) During fiscal 2018, the Company purchased 7.2 million shares of the Company’s Class A Common Stock in a series of open market transactions for $257.6 million . Additionally, the Company repurchased shares during fiscal 2018 to cover the minimum statutory withholding taxes on restricted stock awards and restricted stock units that vested on June 30, 2017 and March 31, 2018. The Company also repurchased shares to cover the minimum statutory withholding taxes on restricted stock for departing officers, as they are no longer subject to a substantial risk of forfeiture. (2) During fiscal 2019, the Company purchased 1.9 million shares of the Company’s Class A Common Stock in a series of open market transactions for $85.4 million . Additionally, the Company repurchased shares during the first quarter of fiscal 2019 to cover the minimum statutory withholding taxes on restricted stock awards and restricted stock units that vested on June 30, 2018. For the quarterly offering period that closed on September 30, 2018 , 56,028 Class A Common Stock shares were purchased by employees under the Company's Employee Stock Purchase Plan, or ESPP. Since the program's inception, 2,307,527 shares have been purchased by employees.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION The following table summarizes stock-based compensation expense recognized in the condensed consolidated statements of operations: Three Months Ended Six Months Ended 2018 2017 2018 2017 Cost of revenue $ 2,534 $ 1,847 $ 3,978 $ 3,306 General and administrative expenses 4,616 4,499 9,286 8,289 Total $ 7,150 $ 6,346 $ 13,264 $ 11,595 The following table summarizes the total stock-based compensation expense recognized in the condensed consolidated statements of operations by the following types of equity awards: Three Months Ended Six Months Ended 2018 2017 2018 2017 Equity Incentive Plan Options $ 586 $ 493 $ 918 $ 969 Class A Restricted Common Stock 6,564 5,853 12,346 10,626 Total $ 7,150 $ 6,346 $ 13,264 $ 11,595 As of September 30, 2018 , there was $32.8 million of total unrecognized compensation cost related to unvested stock-based compensation agreements. The unrecognized compensation cost as of September 30, 2018 is expected to be fully amortized over the next 4.5 years. Absent the effect of accelerating stock compensation cost for any departures of employees who may continue to vest in their equity awards, the following table summarizes the unrecognized compensation cost and the weighted-average period the cost is expected to be amortized. September 30, 2018 Unrecognized Compensation Cost Weighted Average Remaining Period to be Recognized (in years) Equity Incentive Plan Options $ 3,354 3.83 Class A Restricted Common Stock 29,478 2.09 Total $ 32,832 Equity Incentive Plan As of September 30, 2018 , there were 2,326,055 Amended and Restated Equity Incentive Plan options outstanding, of which 753,141 were unvested. Grants of Restricted Stock Units and Class A Restricted Common Stock The following table summarizes grants of Restricted Stock Units ("RSU") and Class A Restricted Common Stock ("RSA") for the quarter ended September 30, 2018 : Grant Date Award Type Shares Awarded Stock Price on Grant Date Total Fair Value July 2, 2018 RSU 21,269 44.59 $ 948 July 25, 2018 RSU 5,551 45.91 255 July 30, 2018 RSU 3,194 44.80 143 August 2, 2018 RSA 39,626 47.45 1,880 69,640 $ 3,226

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The accounting standard for fair value measurements establishes a three-tier value hierarchy, which prioritizes the inputs used in measuring fair value as follows: observable inputs such as quoted prices in active markets (Level 1); inputs other than quoted prices in active markets that are observable either directly or indirectly (Level 2); and unobservable inputs in which there is little or no market data, which requires the Company to develop its own assumptions (Level 3). A financial instrument's level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. The financial instruments measured at fair value in the accompanying condensed consolidated balance sheets consist of the following: Recurring Fair Value Measurements Level 1 Level 2 Level 3 Total Assets: Current derivative instruments (1) $ — $ 2,805 $ — $ 2,805 Long term derivative instruments (1) — 9,128 — 9,128 Long term deferred compensation costs (2) 3,217 — — 3,217 Total Assets $ 3,217 $ 11,933 $ — $ 15,150 Liabilities: Contingent consideration liability (3) $ — $ — $ 3,341 3,341 Long term deferred compensation costs (2) 3,217 — — 3,217 Total Liabilities $ 3,217 $ — $ 3,341 $ 6,558 Recurring Fair Value Measurements Level 1 Level 2 Level 3 Total Assets: Current derivative instruments (1) $ — $ 700 $ — $ 700 Long term derivative instruments (1) — 7,225 — 7,225 Total Assets $ — $ 7,925 $ — $ 7,925 Liabilities: Contingent consideration liability (3) $ — $ — $ 3,576 $ 3,576 Total Liabilities $ — $ — $ 3,576 $ 3,576 (1) The Company’s interest rate swaps are considered over-the-counter derivatives and fair value is estimated based on the present value of future cash flows using a model-derived valuation that uses Level 2 observable inputs such as interest rate yield curves. See Note 9 for further discussion on the Company’s derivative instruments designated as cash flow hedges. (2) Investments in this category consist primarily of mutual funds whose fair values are determined by reference to the quoted market price per unit in active markets multiplied by the number of units held without consideration of transaction costs. These assets represent investments held in a consolidated trust to fund the Company's non-qualified deferred compensation plan and are recorded in other long-term assets and other long-term liabilities on our condensed consolidated balance sheets. (3) The Company recognized a contingent consideration liability of $3.6 million in connection with its acquisition of Aquilent in fiscal 2017. As of September 30, 2018 and March 31, 2018 , the estimated fair value of the contingent consideration liability was $3.3 million and $3.6 million , respectively, and was valued using probability-weighted cash flows, which is based on the use of Level 3 fair value measurement inputs. The liability is recorded in other long-term liabilities in the condensed consolidated balance sheet. The fair value of the Company's cash and cash equivalents, which are primarily Level 1 inputs, approximated its carrying values at September 30, 2018 and March 31, 2018 . The fair value of the Company's debt instruments approximated its carrying value at September 30, 2018 and March 31, 2018 . The fair value of debt is determined using quoted prices or other market information obtained from recent trading activity of each debt tranche in markets that are not active (Level 2 inputs). The fair value is corroborated by prices derived from the interest rate spreads of recently completed leveraged loan transactions of a similar credit profile, industry, and terms to that of the Company. The fair value of the Senior Notes is determined using quoted prices or other market information obtained from recent trading activity in the high-yield bond market (Level 2 inputs).

Related-Party Transactions

Related-Party Transactions	6 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Related-Party Transactions	RELATED-PARTY TRANSACTIONS In March 2017, the Company supported the formation of the Booz Allen Foundation, a nonprofit corporation organized and operated exclusively for charitable, scientific and educational purposes within the meaning of Section 501(c)(3) of the Code. The Company is the sole member of the foundation, which gives it the authority to appoint two of five of the Booz Allen Foundation's directors and consent rights regarding certain extraordinary corporate actions approved by the Company's Board of Directors. The Company has made a binding and irrevocable pledge of $5.0 million to the Booz Allen Foundation and recorded the pledge obligation in other current liabilities on the consolidated balance sheet of the Company in March 2017. As of September 30, 2018 , $1.7 million of the pledge has been paid to the Booz Allen Foundation and is classified as operating activities in the condensed consolidated statement of cash flows.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Letters of Credit and Third-Party Guarantees As of September 30, 2018 and March 31, 2018 , the Company was contingently liable under open standby letters of credit and bank guarantees issued by our banks in favor of third parties that totaled $9.3 million and $6.3 million , respectively. These letters of credit and bank guarantees primarily support insurance and bid and performance obligations. At September 30, 2018 and March 31, 2018 , approximately $1.0 million and $1.4 million , respectively, of these instruments reduced the available borrowings under the Revolving Credit Facility. The remainder is guaranteed under a separate $15.0 million facility established in fiscal 2015 of which $6.7 million and $10.1 million were available to the Company at September 30, 2018 and March 31, 2018 , respectively. Government Contracting Matters For the three months ended September 30, 2018 and 2017 , approximately 96% and 97% of the Company's revenue and for both the six months ended September 30, 2018 and 2017 , approximately 97% of the Company's revenue was generated from contracts where the end user was an agency or department of the U.S. government, including contracts where the Company performed either as a prime contractor or subcontractor, and regardless of the geographic location in which the work was performed. U.S. government contracts and subcontracts are subject to extensive legal and regulatory requirements. From time to time and in the ordinary course of business, agencies of the U.S. government audit our contract costs and conduct inquiries and investigations of our business practices with respect to government contracts to determine whether the Company’s operations are conducted in accordance with these requirements and the terms of the relevant contracts. U.S. government agencies, including the Defense Contract Audit Agency, routinely audit our contract costs, including allocated indirect costs for compliance with the Cost Accounting Standards and the Federal Acquisition Regulation. These agencies also conduct reviews and investigations and make inquiries regarding our accounting and other systems in connection with our performance and business practices with respect to our government contracts and subcontracts. U.S. government audits, inquiries, or investigations of the Company, whether related to the Company's U.S. government contracts or subcontracts or conducted for other reasons, could result in administrative, civil, or criminal liabilities, including withholding of payments, suspension of payments, repayments, fines, or penalties being imposed upon the Company, or could lead to suspension or debarment from future U.S. government contracting. Management believes it has recorded the appropriate provision for any audit, inquiry, or investigation of which it is aware. Management believes it has recorded the appropriate provision for the estimated losses that may be experienced from any such reductions and/or penalties. As of September 30, 2018 and March 31, 2018 , the Company had recorded liabilities of approximately $179.9 million and $168.6 million , respectively, for its current best estimate of amounts to be refunded to customers for potential adjustments from audits or reviews of contract costs incurred subsequent to fiscal year 2011, and for contracts not yet closed that are impacted by settlement of audits or reviews of contract costs incurred in prior fiscal years. Litigation The Company is involved in legal proceedings and investigations arising in the ordinary course of business, including those relating to employment matters, relationships with clients and contractors, intellectual property disputes, and other business matters. These legal proceedings seek various remedies, including claims for monetary damages in varying amounts, none of which are considered material, or are unspecified as to amount. Although the outcome of any such matter is inherently uncertain and may be materially adverse, based on current information, management does not expect any of the currently ongoing audits, reviews, investigations, or litigation to have a material adverse effect on the Company’s financial condition and results of operations. As of September 30, 2018 and March 31, 2018 , there were no material amounts accrued in the condensed consolidated financial statements related to these proceedings. Six former officers and stockholders who had departed the Company prior to the acquisition of the Company by the Carlyle Group (the "Carlyle Acquisition") have filed a total of nine suits in various jurisdictions, with original filing dates ranging from July 3, 2008 through December 15, 2009, against us and certain of our current and former directors and officers. Three of these suits were amended on July 2, 2010 and then further amended into one consolidated complaint on September 7, 2010. Another two of the original nine suits were consolidated into one complaint on September 24, 2014. Each of the suits arises out of the Carlyle Acquisition and alleges that the former stockholders are entitled to certain payments that they would have received if they had held their stock at the time of the Carlyle Acquisition. Some of the suits also allege that the acquisition price paid to stockholders was insufficient. The various suits assert claims for breach of contract, tortious interference with contract, breach of fiduciary duty, civil Racketeer Influenced and Corrupt Organizations Act, or RICO, violations, violations of the ERISA, and/or securities and common law fraud. Three of these suits have been dismissed with all appeals exhausted. The two suits that were consolidated into one action on September 24, 2014 were settled on April 16, 2015. One of the remaining suits has been dismissed by the United States District Court for the Southern District of California and such dismissal was upheld by the United States Court of Appeals for the Ninth Circuit. The plaintiff in this suit subsequently filed a Petition for Writ of Certiorari to the United States Supreme Court, which was denied by the United States Supreme Court on January 9, 2017. The other three remaining suits that were previously consolidated on September 7, 2010 have been dismissed by the United States District Court for the Southern District of New York and were on appeal before the United States Court of Appeals for the Second Circuit. On July 13, 2017, the United States Court of Appeals for the Second Circuit affirmed the ruling of the United States District Court for the Southern District of New York, except for one plaintiff’s securities fraud claim, which was remanded to the United States District Court for the Southern District of New York to give the plaintiff, Paul Kocourek, leave to file another amended complaint to attempt to plead a securities fraud claim. On April 6, 2018, the plaintiff filed an amended complaint in which Mr. Kocourek, individually, as Trustee of the Paul Kocourek Trust and on behalf of a putative class, alleges that the Company and certain former officers and directors violated Sections 10(b), 20(a) and 14(e) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"). On April 25, 2018, the court entered an order postponing the deadline within which the defendants must answer or move to dismiss the amended complaint. A lead plaintiff has not been appointed. On August 2, 2018, the defendants filed a motion to dismiss the amended complaint. On September 17, 2018, the plaintiff filed an opposition to the defendants’ motion to dismiss the amended complaint. The defendants filed their reply to plaintiff's opposition on October 17, 2018. As of September 30, 2018 , the aggregate alleged damages that will be sought in the remaining suit is unknown. As of September 30, 2018 , although the outcome of any of these cases is inherently uncertain and may be materially adverse, based on current information, management does not expect them to have a material adverse effect on our financial condition and results of operations. On June 7, 2017, Booz Allen Hamilton was informed that the U.S. Department of Justice (DOJ) is conducting a civil and criminal investigation of the Company. In connection with the investigation, the DOJ has requested information from the Company relating to certain elements of the Company’s cost accounting and indirect cost charging practices with the U.S. government. Since learning of the investigation, the Company has engaged a law firm experienced in these matters to represent the Company in connection with this matter and respond to the government's requests. As is commonly the case with this type of matter, the Company has also been in contact with other regulatory agencies and bodies, including the Securities and Exchange Commission, which notified the Company that it is conducting an investigation that the Company believes relates to the matters that are also the subject of the DOJ's investigation. The Company may receive additional regulatory or governmental inquiries related to the matters that are the subject of the DOJ's investigation. In accordance with the Company's practice, the Company is cooperating with all relevant government parties. The total cost associated with these matters will depend on many factors, including the duration of these matters and any related findings. At this stage, the Company is not able to reasonably estimate the expected amount or range of cost or any loss associated with these matters. On June 19, 2017, a purported stockholder of the Company filed a putative class action lawsuit in the United States District Court for the Eastern District of Virginia styled Langley v. Booz Allen Hamilton Holding Corp., No. 17-cv-00696 naming the Company, its Chief Executive Officer and its Chief Financial Officer as defendants purportedly on behalf of all purchasers of the Company’s securities from May 19, 2016 through June 15, 2017. On September 5, 2017, the court named two lead plaintiffs, and on October 20, 2017, the lead plaintiffs filed a consolidated amended complaint. The complaint asserts claims under Sections 10(b) and 20(a) of the Exchange Act and Rule 10b-5 promulgated thereunder, alleging misrepresentations or omissions by the Company purporting to relate to matters that are the subject of the DOJ investigation described above. The plaintiffs seek to recover from the Company and the individual defendants an unspecified amount of damages. The Company believes the suit lacks merit and intends to defend against the lawsuit. Motions to dismiss were argued on January 12, 2018, and on February 8, 2018, the court dismissed the amended complaint in its entirety without prejudice. At this stage of the lawsuit, the Company is not able to reasonably estimate the expected amount or range of cost or any loss associated with the lawsuit. On November 13, 2017, a Verified Shareholder Derivative Complaint was filed in the United States District Court for the District of Delaware styled Celine Thum v. Rozanski et. al., C.A. No. 17-cv-01638, naming the Company as a nominal defendant and numerous current and former officers and directors as defendants. The complaint asserts claims for breach of fiduciary duties, unjust enrichment, waste of corporate assets, abuse of control, gross mismanagement, and violations of Sections 14(a), 10(b) and 20(a) of the Exchange Act, purportedly relating to matters that are the subject of the DOJ investigation described above. The parties have stipulated to a stay of the proceedings pending the outcome of the securities litigation (described above), which the court ordered on January 24, 2018. At this stage of the lawsuit, the Company is not able to reasonably estimate the expected amount or range of cost or any loss associated with the lawsuit.

Basis of Presentation (Policies

Basis of Presentation (Policies)	6 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accounting Estimates	Accounting Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expenses during the reporting periods. Areas of the financial statements where estimates may have the most significant effect include contractual and regulatory reserves, valuation and lives of tangible and intangible assets, contingent consideration related to business acquisitions, impairment of long-lived assets, accrued liabilities, revenue recognition, including the accrual of indirect costs, bonus and other incentive compensation, stock-based compensation, reserves for tax benefits and valuation allowances on deferred tax assets, provisions for income taxes, postretirement obligations, certain deferred costs, collectability of receivables, and loss accruals for litigation. Actual results experienced by the Company may differ materially from management's estimates.
Recently Adopted Accounting Standards and Recent Accounting Pronouncements Not Yet Adopted	Recently Adopted Accounting Standards The Company has accounted for the tax effects of the Tax Cuts and Jobs Act, or the 2017 Tax Act, under the guidance of Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act, or SAB 118, on a provisional basis as of the fourth quarter of fiscal 2018. During the three months ended September 30, 2018 , the Company continued its assessment of the 2017 Tax Act, including the potential accounting impact for any new guidance issued during the quarter. The Company made immaterial provisional adjustments associated with the limitation on the deductibility of certain executive compensation based on its preliminary assessment of the recently issued IRS Notice 2018-68. There were no additional changes to the provisional amounts recorded at March 31, 2018. The Company expects to complete its accounting assessment within the prescribed measurement period. See Note 10 to our consolidated financial statements for further information regarding the updated effects of the 2017 Tax Act during the second quarter of fiscal 2019. In May 2014, the Financial Accounting Standards Board, or FASB, issued Accounting Standard Codification No. 606, Revenue from Contracts with Customers (Topic 606). Topic 606, as amended, replaced existing revenue recognition standards by outlining a single set of comprehensive principles for recognizing revenue. The revenue standard also significantly expanded the disclosure requirements for revenue arrangements. Amendments to Topic 606 have generally focused on promoting a more consistent interpretation and application of the principles for recognizing revenue. Topic 606 was effective for the Company beginning on April 1, 2018 (i.e., beginning with the first quarter fiscal 2019 interim financial statements). The Company adopted the new revenue standard using the full retrospective transition method, which requires that it be applied to each prior reporting period presented and that the cumulative effect of applying the standard be recognized at the earliest period presented (i.e., April 1, 2016, the beginning of the first quarter of fiscal 2017). During fiscal 2018, the Company completed its assessment of the cumulative effect of adopting Topic 606 and assessed the impact to be immaterial as of the date of adoption. In August 2018, the FASB issued ASU No. 2018-15, Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract . This guidance requires a customer in a cloud computing arrangement that is a service contract to follow existing internal-use software guidance to determine which implementation costs to defer and recognize as an asset. ASU 2018-15 generally aligns the guidance on capitalizing implementation costs incurred in a cloud computing arrangement that is a service contract with that of implementation costs incurred to develop or obtain internal-use software, including hosting arrangements that include an internal-use software license. ASU 2018-15 is effective for interim reporting periods for fiscal years beginning after December 15, 2019. Early adoption is permitted. The standard may be adopted either retrospectively or prospectively. The Company is currently assessing the future impact of this update on its consolidated financial statements and related disclosures. In August 2017, the FASB issued ASU No. 2017-12, Targeted Improvements to Accounting for Hedging Activities. This guidance eliminates the requirement to separately measure and report hedge ineffectiveness and generally requires, for qualifying hedges, the entire change in the fair value of a hedging instrument to be presented in the same income statement line as the hedged item. Additionally, the guidance also expands an entity's ability to apply hedge accounting for nonfinancial and financial risk components, simplifies the hedge documentation and hedge effectiveness assessment requirements, and modifies certain disclosure requirements. ASU 2017-12 is effective for reporting periods beginning after December 15, 2018, with early adoption permitted. The Company does not expect the adoption of this standard to have a material impact on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), to increase transparency and comparability of accounting for lease transactions. The new leasing standard requires lessees to recognize lease assets and lease liabilities on their balance sheet for all leases with a lease term of greater than 12 months. Lessor accounting is largely unchanged. Topic 842 is effective for fiscal years beginning after December 15, 2018, with early adoption permitted. In July 2018, the FASB provided an alternative transition method of adoption through ASU No. 2018-11, Targeted Improvements , which permits the recognition of a cumulative-effect adjustment to retained earnings on the date of adoption. The Company intends to adopt the standard beginning in fiscal 2020 using the modified retrospective transition approach, specifically, using the alternative transition method provided by ASU 2018-11. A dedicated implementation team has been established that continues to make progress toward completing the evaluation of the impact of the new standard. The Company's assessment efforts to date have included reviewing the provisions of Topic 842, gathering information to evaluate its lease population and portfolio, evaluating the nature of real and personal property and other arrangements that may meet the definition of a lease, designing and implementing one-time implementation controls as well as new post-adoption lease processes and controls, implementing a new lease accounting software solution, and evaluating certain accounting policy elections. The Company anticipates finalizing its accounting policy, accounting software, systems and process modifications during the fourth quarter of fiscal 2019. Based on a preliminary assessment, the Company does not expect there to be a significant change in determining what constitutes a lease, however, the Company expects that virtually all of its operating lease commitments will be subject to the new guidance and recognized as operating lease liabilities and right-of-use assets upon adoption, resulting in a significant increase in the assets and liabilities on its consolidated balance sheets. The pattern of recognition for operating leases within the consolidated statements of operations and comprehensive income is not anticipated to significantly change. The adoption is not expected to impact the Company’s ability to comply with financial covenants as defined within the Company's Sixth Amendment to its Credit Agreement dated July 23, 2018, as discussed further in Note 8, Debt. The Company is continuing to refine its process for quantifying the financial statement impacts and anticipates finalizing its assessment of the materiality of adopting Topic 842 in conjunction with reporting its results for the third quarter of fiscal 2019. In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, Disclosure Update and Simplification , amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders' equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders' equity presented in the balance sheet must be provided in a note or separate statement. The amendments set forth certain presentation requirements, including that such analysis should present a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed with all significant reconciling items described by appropriate captions with contributions from and distributions to owners shown separately. This final rule is effective 30 days after publication in the Federal Register and will generally be effective for the Company for the third quarter of fiscal year 2019. The Company does not expect the adoption of this standard to have a material impact on its consolidated financial statements. Other accounting and reporting pronouncements issued after September 30, 2018 and through the filing date are not expected to have a material impact on the Company's condensed consolidated financial statements.

Basis of Presentation (Tables)

Basis of Presentation (Tables)	6 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	The Company's previously issued condensed consolidated financial statements have been adjusted for the retrospective adoption of both Topic 606 and ASU 2017-07, as summarized in the following table: Three Months Ended September 30, 2017 Six Months Ended September 30, 2017 Effect of Adoption Effect of Adoption As Reported Topic 606 ASU 2017-07 As Adjusted As Reported Topic 606 ASU 2017-07 As Adjusted Revenue $ 1,542,085 $ 720 $ — $ 1,542,805 $ 3,035,655 $ 30,160 $ — $ 3,065,815 Operating income 126,486 4,502 1,901 132,889 265,950 (10,199 ) 3,803 259,554 Income before income taxes 106,091 4,502 — 110,593 227,569 (10,199 ) — 217,370 Net income $ 70,913 $ 2,734 $ — $ 73,647 $ 150,453 $ (6,194 ) $ — $ 144,259 Earnings per common share (Note 4): Basic $ 0.48 $ 0.02 $ — $ 0.50 $ 1.01 $ (0.04 ) $ — $ 0.97 Diluted $ 0.47 $ 0.02 $ — $ 0.49 $ 1.00 $ (0.04 ) $ — $ 0.96

Revenue (Tables)

Revenue (Tables)	6 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenue	The table below presents the total revenue for each type of contract: Three Months Ended Six Months Ended 2018 2017 2018 2017 Cost-reimbursable $ 851,394 53 % $ 795,819 52 % $ 1,711,278 53 % $ 1,565,914 51 % Time-and-materials 390,509 24 % 384,587 25 % 796,093 24 % 766,814 25 % Fixed-price 372,094 23 % 362,399 23 % 753,474 23 % 733,087 24 % Total Revenue $ 1,613,997 100 % $ 1,542,805 100 % $ 3,260,845 100 % $ 3,065,815 100 % Revenue by Customer Type: Three Months Ended Six Months Ended 2018 2017 2018 2017 U.S. government: Defense Clients $ 755,570 47 % $ 706,526 46 % $ 1,513,552 47 % $ 1,418,265 46 % Intelligence Clients 385,733 24 % 379,536 25 % 783,213 24 % 748,005 24 % Civil Clients 417,636 26 % 403,410 26 % 853,162 26 % 808,694 27 % Total U.S. government 1,558,939 97 % 1,489,472 97 % 3,149,927 97 % 2,974,964 97 % Global Commercial Clients 55,058 3 % 53,333 3 % 110,918 3 % 90,851 3 % Total Revenue $ 1,613,997 100 % $ 1,542,805 100 % $ 3,260,845 100 % $ 3,065,815 100 % Revenue by Whether the Company Acts as a Prime Contractor or a Sub-Contractor: Three Months Ended Six Months Ended 2018 2017 2018 2017 Prime Contractor $ 1,482,153 92 % $ 1,413,210 92 % $ 2,989,335 92 % $ 2,801,249 91 % Sub-contractor 131,844 8 % 129,595 8 % 271,510 8 % 264,566 9 % Total Revenue $ 1,613,997 100 % $ 1,542,805 100 % $ 3,260,845 100 % $ 3,065,815 100 %
Summary of Contract Balances	The following table summarizes the contract balances recognized on the Company’s condensed consolidated balance sheets: September 30, March 31, Contract assets: Current $ 749,672 $ 738,646 Long-term 60,093 59,633 Total $ 809,765 $ 798,279 Contract liabilities: Advance payments, billings in excess of costs incurred and deferred revenue $ 22,165 $ 27,522

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Reconciliation of the income used to compute basic and diluted EPS	A reconciliation of the income used to compute basic and diluted EPS for the periods presented are as follows: Three Months Ended Six Months Ended 2018 2017 2018 2017 Earnings for basic computations (1) $ 92,127 $ 72,966 $ 195,681 $ 142,974 Weighted-average common shares outstanding for basic computations 142,443,058 147,085,314 142,861,491 147,400,153 Earnings for diluted computations (1) $ 92,130 $ 72,971 $ 195,690 $ 142,986 Dilutive stock options and restricted stock 1,265,851 1,802,183 1,353,582 1,976,722 Weighted-average common shares outstanding for diluted computations 143,708,909 148,887,497 144,215,073 149,376,875 Earnings per common share Basic $ 0.65 $ 0.50 $ 1.37 $ 0.97 Diluted $ 0.64 $ 0.49 $ 1.36 $ 0.96 (1) During the three months ended September 30, 2018 and 2017 , approximately 0.9 million and 1.4 million participating securities, respectively, were paid dividends totaling $0.2 million in both periods. During the six months ended September 30, 2018 and 2017 , approximately 0.9 million and 1.4 million participating securities, respectively, were paid dividends totaling $0.3 million and $0.4 million , respectively. For the three months ended September 30, 2018 and 2017 , there were undistributed earnings of $0.4 million and $0.4 million , respectively, allocated to the participating class of securities in both basic and diluted EPS. For the six months ended September 30, 2018 and 2017 , there were undistributed earnings of $0.9 million and $0.9 million , respectively, allocated to the participating class of securities in both basic and diluted EPS. The allocated undistributed earnings and the dividends paid comprise the difference between net income presented on the condensed consolidated statements of operations and earnings for basic and diluted computations for the three and six months ended September 30, 2018 and 2017 .

Accounts Receivable, Net of A_2

Accounts Receivable, Net of Allowance (Tables)	6 Months Ended
	Sep. 30, 2018
Receivables [Abstract]
Schedule of Accounts Receivable, Net of Allowance	Accounts receivable, net of allowance consisted of the following: September 30, March 31, Current assets Accounts receivable–billed $ 416,909 $ 395,136 Accounts receivable–unbilled 749,672 738,646 Allowance for doubtful accounts (1,255 ) (77 ) Accounts receivable, net of allowance 1,165,326 1,133,705 Other long-term assets Accounts receivable–unbilled 60,093 59,633 Total accounts receivable, net $ 1,225,419 $ 1,193,338

Accounts Payable and Other Ac_2

Accounts Payable and Other Accrued Expenses (Tables)	6 Months Ended
	Sep. 30, 2018
Payables and Accruals [Abstract]
Schedule of Accounts Payable and Accrued Liabilities	Accounts payable and other accrued expenses consisted of the following: September 30, March 31, Vendor payables $ 377,245 $ 339,993 Accrued expenses 261,017 217,566 Total accounts payable and other accrued expenses $ 638,262 $ 557,559

Accrued Compensation and Bene_2

Accrued Compensation and Benefits (Tables)	6 Months Ended
	Sep. 30, 2018
Compensation Related Costs [Abstract]
Schedule of accrued compensation and benefits	Accrued compensation and benefits consisted of the following: September 30, March 31, Bonus $ 44,105 $ 87,817 Retirement 66,411 35,743 Vacation 135,233 131,519 Other 26,212 27,671 Total accrued compensation and benefits $ 271,961 $ 282,750

Debt (Tables)

Debt (Tables)	6 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Schedule of Debt	Debt consisted of the following: September 30, 2018 March 31, 2018 Interest Rate Outstanding Balance Interest Rate Outstanding Balance Term Loan A 3.74 % $ 1,064,700 3.88 % $ 1,094,275 Term Loan B 4.24 % 393,025 3.88 % 395,000 Senior Notes 5.13 % 350,000 5.13 % 350,000 Less: Unamortized debt issuance costs and discount on debt (20,926 ) (20,696 ) Total 1,786,799 1,818,579 Less: Current portion of long-term debt (63,100 ) (63,100 ) Long-term debt, net of current portion $ 1,723,699 $ 1,755,479
Schedule of Interest Expense	Interest on debt and debt-like instruments consisted of the following: Three Months Ended Six Months Ended 2018 2017 2018 2017 (In thousands) (In thousands) Term Loan A Interest Expense $ 10,345 $ 9,394 $ 21,187 $ 18,171 Term Loan B Interest Expense 4,115 3,518 8,032 6,791 Interest on Revolving Credit Facility 2 199 61 199 Senior Notes Interest Expense 4,485 4,484 8,969 7,773 Deferred Payment Obligation Interest (1) 1,993 2,011 4,015 4,022 Amortization of Debt Issuance Cost (DIC) and Original Issue Discount (OID) (2) 1,258 1,343 2,618 2,633 Other 49 9 439 116 Total Interest Expense $ 22,247 $ 20,958 $ 45,321 $ 39,705 (1) Interest payments on the deferred payment obligation are made twice a year in January and July. (2) DIC and OID on the Term Loans and Senior Notes are recorded as a reduction of long-term debt in the condensed consolidated balance sheet and are amortized ratably over the life of the related debt using the effective rate method. DIC on the Revolving Credit Facility is recorded as a long-term asset on the condensed consolidated balance sheet and amortized ratably over the term of the Revolving Credit Facility.

Other Long-Term Liabilities (Ta

Other Long-Term Liabilities (Tables)	6 Months Ended
	Sep. 30, 2018
Other Liabilities Disclosure [Abstract]
Summary of Other Long-Term Liabilities	Other long-term liabilities consisted of the following: September 30, March 31, Deferred rent $ 77,323 $ 79,913 Postretirement benefit obligations 135,191 131,526 Other (1) 48,035 48,443 Total other long-term liabilities $ 260,549 $ 259,882 (1) Balances at September 30, 2018 and March 31, 2018 include the Company's long-term disability obligation of $22.8 million for both periods as well as contingent consideration related to the Company's business acquisition of an acquiree in the fourth quarter of fiscal 2017 of $3.3 million and $3.6 million , respectively.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	6 Months Ended
	Sep. 30, 2018
Retirement Benefits [Abstract]
Components of net postretirement medical expense	The components of net postretirement medical expense for the Officer Medical Plan were as follows: Three Months Ended Six Months Ended 2018 2017 2018 2017 Service cost $ 1,488 $ 1,116 $ 2,976 $ 2,232 Interest cost 1,282 1,252 2,564 2,504 Net actuarial loss 527 568 1,054 1,135 Total postretirement medical expense $ 3,297 $ 2,936 $ 6,594 $ 5,871

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	6 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Schedule of accumulated other comprehensive loss	The following table shows the changes in accumulated other comprehensive income (loss), net of tax: Three Months Ended September 30, 2018 Six Months Ended September 30, 2018 Post-retirement plans Derivatives designated as cash flow hedges Totals Post-retirement plans Derivatives designated as cash flow hedges Totals Beginning of period $ (20,548 ) $ 7,769 $ (12,779 ) $ (20,955 ) $ 5,849 $ (15,106 ) Other comprehensive income (loss) before reclassifications (1) — 1,154 1,154 — 3,041 3,041 Amounts reclassified from accumulated other comprehensive loss 424 (116 ) 308 831 (83 ) 748 Net current-period other comprehensive income (loss) 424 1,038 1,462 831 2,958 3,789 End of period $ (20,124 ) $ 8,807 $ (11,317 ) $ (20,124 ) $ 8,807 $ (11,317 ) (1) Changes in other comprehensive income (loss) before reclassification for derivatives designated as cash flow hedges are recorded net of tax expenses of $0.4 million and $1.1 million for the three and six months ended September 30, 2018 , respectively. Three Months Ended September 30, 2017 Six Months Ended September 30, 2017 Post-retirement plans Derivatives designated as cash flow hedges Totals Post-retirement plans Derivatives designated as cash flow hedges Totals Beginning of period $ (16,714 ) $ (510 ) $ (17,224 ) $ (17,077 ) $ — $ (17,077 ) Other comprehensive income (loss) before reclassifications (2) — (124 ) (124 ) — (634 ) (634 ) Amounts reclassified from accumulated other comprehensive loss 361 — 361 724 — 724 Net current-period other comprehensive income (loss) 361 (124 ) 237 724 (634 ) 90 End of period $ (16,353 ) $ (634 ) $ (16,987 ) $ (16,353 ) $ (634 ) $ (16,987 ) (2) Changes in other comprehensive income (loss) before reclassification for derivatives designated as cash flow hedges are recorded net of tax benefits of $0.1 million and $0.4 million for the three and six months ended September 30, 2017 , respectively.
Reclassification out of accumulated other comprehensive loss to net income	The following table presents the reclassifications out of accumulated other comprehensive loss to net income: Three Months Ended Six Months Ended 2018 2017 2018 2017 Amounts reclassified from accumulated other comprehensive loss: Post-retirement plans (Note 12): Amortization of net actuarial loss included in net periodic benefit cost $ 551 $ 596 $ 1,101 $ 1,193 Tax benefit (expense) (127 ) (235 ) (270 ) (469 ) Net of tax $ 424 $ 361 $ 831 $ 724

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Sep. 30, 2018
Equity [Abstract]
Schedule of Common Stock Outstanding	The common stock shares activity consisted of the following: Class A Common Stock Treasury Stock Balance at March 31, 2017 155,901,485 7,013,777 Issuance of common stock 866,099 — Stock options exercised 1,261,089 — Repurchase of common stock (1) — 7,568,357 Balance at March 31, 2018 158,028,673 14,582,134 Issuance of common stock 417,366 — Stock options exercised 678,173 — Repurchase of common stock (2) — 1,991,299 Balance at September 30, 2018 159,124,212 16,573,433 (1) During fiscal 2018, the Company purchased 7.2 million shares of the Company’s Class A Common Stock in a series of open market transactions for $257.6 million . Additionally, the Company repurchased shares during fiscal 2018 to cover the minimum statutory withholding taxes on restricted stock awards and restricted stock units that vested on June 30, 2017 and March 31, 2018. The Company also repurchased shares to cover the minimum statutory withholding taxes on restricted stock for departing officers, as they are no longer subject to a substantial risk of forfeiture. (2) During fiscal 2019, the Company purchased 1.9 million shares of the Company’s Class A Common Stock in a series of open market transactions for $85.4 million . Additionally, the Company repurchased shares during the first quarter of fiscal 2019 to cover the minimum statutory withholding taxes on restricted stock awards and restricted stock units that vested on June 30, 2018.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Stock-Based Compensation Expense Recognized in the Condensed Consolidated Statements of Operations	The following table summarizes stock-based compensation expense recognized in the condensed consolidated statements of operations: Three Months Ended Six Months Ended 2018 2017 2018 2017 Cost of revenue $ 2,534 $ 1,847 $ 3,978 $ 3,306 General and administrative expenses 4,616 4,499 9,286 8,289 Total $ 7,150 $ 6,346 $ 13,264 $ 11,595 The following table summarizes the total stock-based compensation expense recognized in the condensed consolidated statements of operations by the following types of equity awards: Three Months Ended Six Months Ended 2018 2017 2018 2017 Equity Incentive Plan Options $ 586 $ 493 $ 918 $ 969 Class A Restricted Common Stock 6,564 5,853 12,346 10,626 Total $ 7,150 $ 6,346 $ 13,264 $ 11,595
Schedule of Unrecognized Compensation Cost	Absent the effect of accelerating stock compensation cost for any departures of employees who may continue to vest in their equity awards, the following table summarizes the unrecognized compensation cost and the weighted-average period the cost is expected to be amortized. September 30, 2018 Unrecognized Compensation Cost Weighted Average Remaining Period to be Recognized (in years) Equity Incentive Plan Options $ 3,354 3.83 Class A Restricted Common Stock 29,478 2.09 Total $ 32,832
Summary of Grants of Restricted Stock Units and Restricted Stock Awards	The following table summarizes grants of Restricted Stock Units ("RSU") and Class A Restricted Common Stock ("RSA") for the quarter ended September 30, 2018 : Grant Date Award Type Shares Awarded Stock Price on Grant Date Total Fair Value July 2, 2018 RSU 21,269 44.59 $ 948 July 25, 2018 RSU 5,551 45.91 255 July 30, 2018 RSU 3,194 44.80 143 August 2, 2018 RSA 39,626 47.45 1,880 69,640 $ 3,226

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of Recurring Fair Value Measurements	The financial instruments measured at fair value in the accompanying condensed consolidated balance sheets consist of the following: Recurring Fair Value Measurements Level 1 Level 2 Level 3 Total Assets: Current derivative instruments (1) $ — $ 2,805 $ — $ 2,805 Long term derivative instruments (1) — 9,128 — 9,128 Long term deferred compensation costs (2) 3,217 — — 3,217 Total Assets $ 3,217 $ 11,933 $ — $ 15,150 Liabilities: Contingent consideration liability (3) $ — $ — $ 3,341 3,341 Long term deferred compensation costs (2) 3,217 — — 3,217 Total Liabilities $ 3,217 $ — $ 3,341 $ 6,558 Recurring Fair Value Measurements Level 1 Level 2 Level 3 Total Assets: Current derivative instruments (1) $ — $ 700 $ — $ 700 Long term derivative instruments (1) — 7,225 — 7,225 Total Assets $ — $ 7,925 $ — $ 7,925 Liabilities: Contingent consideration liability (3) $ — $ — $ 3,576 $ 3,576 Total Liabilities $ — $ — $ 3,576 $ 3,576 (1) The Company’s interest rate swaps are considered over-the-counter derivatives and fair value is estimated based on the present value of future cash flows using a model-derived valuation that uses Level 2 observable inputs such as interest rate yield curves. See Note 9 for further discussion on the Company’s derivative instruments designated as cash flow hedges. (2) Investments in this category consist primarily of mutual funds whose fair values are determined by reference to the quoted market price per unit in active markets multiplied by the number of units held without consideration of transaction costs. These assets represent investments held in a consolidated trust to fund the Company's non-qualified deferred compensation plan and are recorded in other long-term assets and other long-term liabilities on our condensed consolidated balance sheets. (3) The Company recognized a contingent consideration liability of $3.6 million in connection with its acquisition of Aquilent in fiscal 2017. As of September 30, 2018 and March 31, 2018 , the estimated fair value of the contingent consideration liability was $3.3 million and $3.6 million , respectively, and was valued using probability-weighted cash flows, which is based on the use of Level 3 fair value measurement inputs. The liability is recorded in other long-term liabilities in the condensed consolidated balance sheet.

Business Overview (Details)

Business Overview (Details)	6 Months Ended
	Sep. 30, 2018employeesegment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments | segment	1
Number of employees | employee	25,300

Basis of Presentation - Narrati

Basis of Presentation - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Mar. 31, 2018	Sep. 30, 2018	Mar. 31, 2017	Mar. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Increase (decrease) in retained earnings			$ 690,516	$ 832,774
Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Cumulative effect on retained earnings			7,900
Restatement Adjustment | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Increase (decrease) in retained earnings			$ (3,400)		$ 8,400	$ 2,900
Restatement Adjustment | Accounting Standards Update 2017-07
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Reclassification of net periodic benefit cost	$ 1,900	$ 3,800

Basis of Presentation - Consoli

Basis of Presentation - Consolidated Statements of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	$ 1,613,997	$ 1,542,805	$ 3,260,845	$ 3,065,815
Operating income	143,751	132,889	305,363	259,554
Income before income taxes	119,887	110,593	257,254	217,370
Net income	$ 92,713	$ 73,647	$ 196,917	$ 144,259
Earnings per common share, basic (in dollars per share)	$ 0.65	$ 0.50	$ 1.37	$ 0.97
Earnings per common share, diluted (in dollars per shares)	$ 0.64	$ 0.49	$ 1.36	$ 0.96
Restatement Adjustment | Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue		$ 720		$ 30,160
Operating income		4,502		(10,199)
Income before income taxes		4,502		(10,199)
Net income		$ 2,734		$ (6,194)
Earnings per common share, basic (in dollars per share)		$ 0.02		$ (0.04)
Earnings per common share, diluted (in dollars per shares)		$ 0.02		$ (0.04)
Restatement Adjustment | ASU 2017-07
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue		$ 0		$ 0
Operating income		1,901		3,803
Income before income taxes		0		0
Net income		$ 0		$ 0
Earnings per common share, basic (in dollars per share)		$ 0		$ 0
Earnings per common share, diluted (in dollars per shares)		$ 0		$ 0
Previously Reported
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue		$ 1,542,085		$ 3,035,655
Operating income		126,486		265,950
Income before income taxes		106,091		227,569
Net income		$ 70,913		$ 150,453
Earnings per common share, basic (in dollars per share)		$ 0.48		$ 1.01
Earnings per common share, diluted (in dollars per shares)		$ 0.47		$ 1

Revenue - Narrative (Details)

Revenue - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue from Contract with Customer [Abstract]
Revenue, amount of remaining performance obligation	$ 7,800		$ 7,800
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract with customer, liability, revenue recognized	$ 3.8	$ 0.8	$ 10.6	$ 6.6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, expected timing, period one			12 months
Remaining performance obligation, expected timing, period two			24 months
Remaining performance obligation, percentage	75.00%		75.00%

Revenue - Schedules of Disaggre

Revenue - Schedules of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenue	$ 1,613,997	$ 1,542,805	$ 3,260,845	$ 3,065,815
Total revenue (as a percent)	100.00%	100.00%	100.00%	100.00%
Prime Contractor
Disaggregation of Revenue [Line Items]
Revenue	$ 1,482,153	$ 1,413,210	$ 2,989,335	$ 2,801,249
Total revenue (as a percent)	92.00%	92.00%	92.00%	91.00%
Sub-contractor
Disaggregation of Revenue [Line Items]
Revenue	$ 131,844	$ 129,595	$ 271,510	$ 264,566
Total revenue (as a percent)	8.00%	8.00%	8.00%	9.00%
UNITED STATES
Disaggregation of Revenue [Line Items]
Revenue	$ 1,558,939	$ 1,489,472	$ 3,149,927	$ 2,974,964
Total revenue (as a percent)	97.00%	97.00%	97.00%	97.00%
Defense Clients | UNITED STATES
Disaggregation of Revenue [Line Items]
Revenue	$ 755,570	$ 706,526	$ 1,513,552	$ 1,418,265
Total revenue (as a percent)	47.00%	46.00%	47.00%	46.00%
Intelligence Clients | UNITED STATES
Disaggregation of Revenue [Line Items]
Revenue	$ 385,733	$ 379,536	$ 783,213	$ 748,005
Total revenue (as a percent)	24.00%	25.00%	24.00%	24.00%
Civil Clients | UNITED STATES
Disaggregation of Revenue [Line Items]
Revenue	$ 417,636	$ 403,410	$ 853,162	$ 808,694
Total revenue (as a percent)	26.00%	26.00%	26.00%	27.00%
Global Commercial Clients
Disaggregation of Revenue [Line Items]
Revenue	$ 55,058	$ 53,333	$ 110,918	$ 90,851
Total revenue (as a percent)	3.00%	3.00%	3.00%	3.00%
Cost-reimbursable
Disaggregation of Revenue [Line Items]
Revenue	$ 851,394	$ 795,819	$ 1,711,278	$ 1,565,914
Total revenue (as a percent)	53.00%	52.00%	53.00%	51.00%
Time-and-materials
Disaggregation of Revenue [Line Items]
Revenue	$ 390,509	$ 384,587	$ 796,093	$ 766,814
Total revenue (as a percent)	24.00%	25.00%	24.00%	25.00%
Fixed-price
Disaggregation of Revenue [Line Items]
Revenue	$ 372,094	$ 362,399	$ 753,474	$ 733,087
Total revenue (as a percent)	23.00%	23.00%	23.00%	24.00%

Revenue - Schedule of Contract

Revenue - Schedule of Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Contract assets:
Current	$ 749,672	$ 738,646
Long-term	60,093	59,633
Total	809,765	798,279
Contract liabilities:
Advance payments, billings in excess of costs incurred and deferred revenue	$ 22,165	$ 27,522

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Earnings for basic computations	$ 92,127	$ 72,966	$ 195,681	$ 142,974
Earnings for diluted computations	$ 92,130	$ 72,971	$ 195,690	$ 142,986
Dilutive stock options and restricted stock (in shares)	1,265,851	1,802,183	1,353,582	1,976,722
Earnings per common share
Basic (in dollars per share)	$ 0.65	$ 0.50	$ 1.37	$ 0.97
Diluted (in dollars per share)	$ 0.64	$ 0.49	$ 1.36	$ 0.96
Unvested shares, cash dividends paid			$ 54,660	$ 50,866
Restricted stock
Earnings per common share
Unvested shares participating in the payment of the Company's dividends declared	900,000	1,400,000	900,000	1,400,000
Unvested shares, cash dividends paid	$ 200	$ 200	$ 300	$ 400
Undistributed earnings allocated to participating securities, basic	400	400	900	900
Undistributed earnings allocated to participating securities, diluted	$ 400	$ 400	$ 900	$ 900
Stock options
Earnings per common share
Antidilutive options excluded from the computation of EPS	200,000	400,000	200,000	300,000
Class A Common Stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted-average common shares outstanding for basic computations	142,443,058	147,085,314	142,861,491	147,400,153
Weighted-average common shares outstanding for diluted computations	143,708,909	148,887,497	144,215,073	149,376,875

Accounts Receivable, Net of A_3

Accounts Receivable, Net of Allowance (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Mar. 31, 2018
Current assets
Accounts receivable–billed	$ 416,909		$ 416,909	$ 395,136
Accounts receivable–unbilled	749,672		749,672	738,646
Allowance for doubtful accounts	(1,255)		(1,255)	(77)
Accounts receivable, net of allowance	1,165,326		1,165,326	1,133,705
Other long-term assets
Accounts receivable–unbilled	60,093		60,093	59,633
Total accounts receivable, net	1,225,419		1,225,419	1,193,338
Provision for doubtful accounts	$ 10,600	$ 2,200	$ 10,700	$ 3,100

Accounts Payable and Other Ac_3

Accounts Payable and Other Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Payables and Accruals [Abstract]
Vendor payables	$ 377,245	$ 339,993
Accrued expenses	261,017	217,566
Total accounts payable and other accrued expenses	$ 638,262	$ 557,559

Accrued Compensation and Bene_3

Accrued Compensation and Benefits (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Compensation Related Costs [Abstract]
Bonus	$ 44,105	$ 87,817
Retirement	66,411	35,743
Vacation	135,233	131,519
Other	26,212	27,671
Total accrued compensation and benefits	$ 271,961	$ 282,750

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jul. 23, 2018	Jul. 22, 2018	Mar. 31, 2018
Long-term Debt, Current and Noncurrent [Abstract]
Less: Unamortized debt issuance costs and discount on debt	$ (20,926)			$ (20,696)
Total	1,786,799			1,818,579
Less: Current portion of long-term debt	(63,100)			(63,100)
Long-term debt, net of current portion	$ 1,723,699			$ 1,755,479
Secured Debt | Term Loan A
Long-term Debt, Current and Noncurrent [Abstract]
Interest rate	3.74%			3.88%
Long-term debt outstanding	$ 1,064,700	$ 1,479,500	$ 1,079,500	$ 1,094,275
Secured Debt | Term Loan B
Long-term Debt, Current and Noncurrent [Abstract]
Interest rate	4.24%			3.88%
Long-term debt outstanding	$ 393,025			$ 395,000
Senior Notes | Senior Notes
Long-term Debt, Current and Noncurrent [Abstract]
Interest rate	5.13%			5.13%
Long-term debt outstanding	$ 350,000			$ 350,000

Debt - Narrative (Details)

Debt - Narrative (Details)	Jul. 23, 2018USD ($)occasion	Jul. 22, 2018USD ($)	Jun. 30, 2018USD ($)	Sep. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Apr. 25, 2017USD ($)
Debt Instrument [Line Items]
Long-term debt, maximum expanded loan facility				$ 627,000,000
Percentage of consolidated EBITDA required for expansion of loan				100.00%
Net secured leverage ratio				350.00%
Delayed Draw Facility
Debt Instrument [Line Items]
Revolving credit facility, maximum borrowing capacity	$ 400,000,000
Number of draws allowed on facility | occasion	2
Minimum amount per draw on facility	$ 100,000,000
Term Loan B | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Long-term debt, basis spread on variable rate				2.00%
Term Loan B | Base Rate
Debt Instrument [Line Items]
Long-term debt, basis spread on variable rate				1.00%
Term Loan A | Minimum
Debt Instrument [Line Items]
Long-term debt, basis spread on variable rate	1.25%	1.50%
Term Loan A | Maximum
Debt Instrument [Line Items]
Long-term debt, basis spread on variable rate	2.00%	2.25%
Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility, maximum borrowing capacity		$ 500,000,000		$ 500,000,000
Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Minimum
Debt Instrument [Line Items]
Long-term debt, basis spread on variable rate				1.50%
Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Maximum
Debt Instrument [Line Items]
Long-term debt, basis spread on variable rate				2.25%
Revolving Credit Facility | Base Rate | Minimum
Debt Instrument [Line Items]
Long-term debt, basis spread on variable rate				0.50%
Revolving Credit Facility | Base Rate | Maximum
Debt Instrument [Line Items]
Long-term debt, basis spread on variable rate				1.25%
Secured Debt | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Long-term debt, basis spread on variable rate				1.00%
Secured Debt | London Interbank Offered Rate (LIBOR) | Minimum
Debt Instrument [Line Items]
Long-term debt, basis spread on variable rate				0.00%
Secured Debt | Overnight Federal Funds Rate
Debt Instrument [Line Items]
Long-term debt, basis spread on variable rate				0.50%
Secured Debt | Base Rate | Minimum
Debt Instrument [Line Items]
Long-term debt, basis spread on variable rate				0.00%
Secured Debt | Term Loan B
Debt Instrument [Line Items]
Long-term debt outstanding				$ 393,025,000	$ 395,000,000
Quarterly periodic payment percentage, principal				0.25%
Secured Debt | Term Loan A
Debt Instrument [Line Items]
Long-term debt outstanding	$ 1,479,500,000	$ 1,079,500,000		$ 1,064,700,000	1,094,275,000
Quarterly periodic payment percentage, principal				1.25%
Secured Debt | Term Loan A | Base Rate | Minimum
Debt Instrument [Line Items]
Long-term debt, basis spread on variable rate				0.25%
Secured Debt | Term Loan A | Base Rate | Maximum
Debt Instrument [Line Items]
Long-term debt, basis spread on variable rate				1.00%
Secured Debt | Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Commitment fee percentage				0.20%
Secured Debt | Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Commitment fee percentage				0.35%
Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility, maximum borrowing capacity				$ 500,000,000
Proceeds from lines of credit				70,000,000
Revolving credit facility, amount outstanding				0	0
Letter of Credit
Debt Instrument [Line Items]
Revolving credit facility, maximum borrowing capacity				100,000,000
Senior Notes | Senior Notes due 2025
Debt Instrument [Line Items]
Long-term debt outstanding				350,000,000	$ 350,000,000
Term loan, face amount						$ 350,000,000
Debt instrument, stated percentage						5.125%
Debt issuance costs						$ 6,700,000
Interest			$ 9,000,000	$ 9,000,000

Debt - Schedule of Interest Exp

Debt - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Debt Instrument [Line Items]
Deferred Payment Obligation Interest	$ 1,993	$ 2,011	$ 4,015	$ 4,022
Amortization of Debt Issuance Cost (DIC) and Original Issue Discount (OID)	1,258	1,343	2,618	2,633
Other	49	9	439	116
Total Interest Expense	22,247	20,958	45,321	39,705
Secured Debt | Term Loan A
Debt Instrument [Line Items]
Interest expense on debt	10,345	9,394	21,187	18,171
Secured Debt | Term Loan B
Debt Instrument [Line Items]
Interest expense on debt	4,115	3,518	8,032	6,791
Revolving Credit Facility
Debt Instrument [Line Items]
Interest expense on debt	2	199	61	199
Senior Notes
Debt Instrument [Line Items]
Interest expense on debt	$ 4,485	$ 4,484	$ 8,969	$ 7,773

Derivatives (Details)

Derivatives (Details) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Other Current Assets
Derivative [Line Items]
Fair value of derivative assets	$ 2,800,000	$ 700,000	$ 2,800,000	$ 700,000
Long-term assets
Derivative [Line Items]
Fair value of derivative assets	9,100,000	7,200,000	9,100,000	7,200,000
Designated as Hedging Instrument | Cash Flow Hedging | Interest Rate Swap
Derivative [Line Items]
Notional amount	450,000,000		450,000,000
Gain (loss) recognized in AOCI	1,200,000	(100,000)	3,000,000	(600,000)
Amounts reclassified into earnings	100,000	$ 0	80,000	$ 0
Ineffectiveness recognized in earnings			0
Estimate of amount to be reclassified over the next 12 months	$ 2,800,000		$ 2,800,000

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2019
Operating Loss Carryforwards [Line Items]
Tax Act, measurement period adjustment to executive compensation	$ 1,100
Tax Act, measurement period adjustment to income tax expense	$ 1,100
Tax Act, effective tax rate, percent	0.90%
Income tax benefit	$ (27,174)	$ (36,946)	$ (60,337)	$ (73,111)
Effective income tax rate	22.70%	33.40%	23.50%	33.60%
Income tax uncertainty	$ 10,200		$ 10,200
Tax Years 2013-2015
Operating Loss Carryforwards [Line Items]
Income tax assessments			11,500
Tax Years 2016-2018
Operating Loss Carryforwards [Line Items]
Income tax assessments			$ 28,300
Subsequent Event | Revenue Recognition For Income Tax Purposes, Unbilled Receivables | Scenario, Forecast
Operating Loss Carryforwards [Line Items]
Income tax benefit					$ 28,900

Other Long-Term Liabilities (De

Other Long-Term Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Other Liabilities Disclosure [Abstract]
Deferred rent	$ 77,323	$ 79,913
Postretirement benefit obligations	135,191	131,526
Other	48,035	48,443
Total other long-term liabilities	260,549	259,882
Long-term disability obligation	$ 22,800	22,800
Aquilent
Business Acquisition [Line Items]
Acquisition-related contingent consideration		$ 3,600

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018
Retirement Benefits [Abstract]
Employer matching contribution, percent of match			6.00%
Employees’ capital accumulation plan, total expense recognized	$ 33,600,000	$ 30,700,000	$ 66,200,000	$ 61,800,000
Employees’ capital accumulation plan, company-paid contributions	16,900,000	15,500,000	$ 34,400,000	31,100,000
Defined Benefit Plan Disclosure [Line Items]
Maximum eligible deferral of compensation, percentage			100.00%
Deferred compensation plan, assets	3,200,000		$ 3,200,000
Deferred compensation plan, liabilities	3,100,000		3,100,000
Supplemental Employee Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Deferred compensation arrangement with individual, annual cash award granted per year of service, amount			10,000
Officer Medical Plan | Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,488,000	1,116,000	2,976,000	2,232,000
Interest cost	1,282,000	1,252,000	2,564,000	2,504,000
Net actuarial loss	527,000	568,000	1,054,000	1,135,000
Total postretirement medical expense	3,297,000	$ 2,936,000	6,594,000	$ 5,871,000
Defined benefit plan, unfunded status of plan	$ 130,500,000		$ 130,500,000		$ 126,900,000

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss - Schedule of Changes in AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period			$ 562,491
Total other comprehensive income (loss), net of tax	$ 1,462	$ 237	3,789	$ 90
End of period	646,340		646,340
Post-retirement plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period	(20,548)	(16,714)	(20,955)	(17,077)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive loss	424	361	831	724
Total other comprehensive income (loss), net of tax	424	361	831	724
End of period	(20,124)	(16,353)	(20,124)	(16,353)
Derivatives designated as cash flow hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period	7,769	(510)	5,849	0
Other comprehensive income (loss) before reclassifications	1,154	(124)	3,041	(634)
Amounts reclassified from accumulated other comprehensive loss	(116)	0	(83)	0
Total other comprehensive income (loss), net of tax	1,038	(124)	2,958	(634)
End of period	8,807	(634)	8,807	(634)
Other comprehensive income (loss) before reclassifications, tax	400	(100)	1,100	(400)
Totals
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period	(12,779)	(17,224)	(15,106)	(17,077)
Other comprehensive income (loss) before reclassifications	1,154	(124)	3,041	(634)
Amounts reclassified from accumulated other comprehensive loss	308	361	748	724
Total other comprehensive income (loss), net of tax	1,462	237	3,789	90
End of period	$ (11,317)	$ (16,987)	$ (11,317)	$ (16,987)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Loss - Reclassifications out of Accumulated Other Comprehensive Loss to Net Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	$ 119,887	$ 110,593	$ 257,254	$ 217,370
Tax benefit	(27,174)	(36,946)	(60,337)	(73,111)
Net of tax	92,713	73,647	196,917	144,259
Reclassification out of Accumulated Other Comprehensive Income | Post-retirement Plans
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	551	596	1,101	1,193
Tax benefit	(127)	(235)	(270)	(469)
Net of tax	$ 424	$ 361	$ 831	$ 724

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock Shares Activity (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Sep. 30, 2018	Mar. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury stock, beginning balance (shares)	14,582,134	7,013,777
Repurchase of common stock (in shares)	1,991,299	7,568,357
Treasury stock, ending balance (shares)	16,573,433	14,582,134
Class A Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (shares)	158,028,673	155,901,485
Issuance of common stock (shares)	417,366	866,099
Stock options exercised (shares)	678,173	1,261,089
Ending balance (shares)	159,124,212	158,028,673
Repurchase of common stock (in shares)	1,900,000	7,200,000
Repurchase of common stock, value, cost method	$ 85.4	$ 257.6

Stockholders' Equity - Employee

Stockholders' Equity - Employee Stock Purchase Plan (Details) - shares	3 Months Ended	95 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock purchased by employees (in shares)	56,028	2,307,527

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 7,150	$ 6,346	$ 13,264	$ 11,595
Stock options | EIP
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	586	493	918	969
Restricted stock | Annual Incentive Plan | Class A Common Stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	6,564	5,853	12,346	10,626
Cost of revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	2,534	1,847	3,978	3,306
General and administrative expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 4,616	$ 4,499	$ 9,286	$ 8,289

Stock-Based Compensation - Unre

Stock-Based Compensation - Unrecognized Compensation (Details) $ in Thousands	6 Months Ended
	Sep. 30, 2018USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested stock-based compensation agreements	$ 32,832
Unrecognized compensation cost, amortization period	4 years 6 months
EIP | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested stock-based compensation agreements	$ 3,354
Unrecognized compensation cost, amortization period	3 years 10 months
Annual Incentive Plan | Restricted stock | Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested stock-based compensation agreements	$ 29,478
Unrecognized compensation cost, amortization period	2 years 1 month 3 days

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 02, 2018	Jul. 30, 2018	Jul. 25, 2018	Jul. 02, 2018	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock granted (in shares)					69,640
Restricted stock, total fair value					$ 3,226
Stock options | EIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options outstanding (in shares)					2,326,055
Stock options outstanding, unvested (in shares)					753,141
Restricted stock units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock granted (in shares)		3,194	5,551	21,269
Stock price on grant date (in dollars per share)		$ 44.80	$ 45.91	$ 44.59
Restricted stock, total fair value		$ 143	$ 255	$ 948
Class A Common Stock | Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock granted (in shares)	39,626
Stock price on grant date (in dollars per share)	$ 47.45
Restricted stock, total fair value	$ 1,880

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Assets, Fair Value Disclosure [Abstract]
Long term deferred compensation costs	$ 3,200
Liabilities, Fair Value Disclosure [Abstract]
Long term deferred compensation costs	3,100
Fair Value, Measurements, Recurring
Assets, Fair Value Disclosure [Abstract]
Current derivative instruments	2,805	$ 700
Long term derivative instruments	9,128	7,225
Long term deferred compensation costs	3,217
Total Assets	15,150	7,925
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration, liability	3,341	3,576
Long term deferred compensation costs	3,217
Total Liabilities	6,558	3,576
Fair Value, Measurements, Recurring | Level 1
Assets, Fair Value Disclosure [Abstract]
Current derivative instruments	0	0
Long term derivative instruments	0	0
Long term deferred compensation costs	3,217
Total Assets	3,217	0
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration, liability	0	0
Long term deferred compensation costs	3,217
Total Liabilities	3,217	0
Fair Value, Measurements, Recurring | Level 2
Assets, Fair Value Disclosure [Abstract]
Current derivative instruments	2,805	700
Long term derivative instruments	9,128	7,225
Long term deferred compensation costs	0
Total Assets	11,933	7,925
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration, liability	0	0
Long term deferred compensation costs	0
Total Liabilities	0	0
Fair Value, Measurements, Recurring | Level 3
Assets, Fair Value Disclosure [Abstract]
Current derivative instruments	0	0
Long term derivative instruments	0	0
Long term deferred compensation costs	0
Total Assets	0	0
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration, liability	3,341	3,576
Long term deferred compensation costs	0
Total Liabilities	3,341	3,576
Other noncurrent liabilities | Fair Value, Measurements, Recurring | Level 3
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration, liability	$ 3,300	$ 3,600

Related-Party Transactions (Det

Related-Party Transactions (Details) - Affiliated Entity - Pledge Obligation - USD ($)	6 Months Ended
	Sep. 30, 2018	Mar. 31, 2017
Related Party Transaction [Line Items]
Due to affiliate, current		$ 5,000,000
Payment of pledge obligation	$ 1,700,000

Commitments and Contingencies -

Commitments and Contingencies - Guarantees and Contracts (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2018	Mar. 31, 2015
Contracts with U.S. government agencies or other U.S. government contractors
Concentration Risk [Line Items]
Concentration risk, percentage	96.00%	97.00%	97.00%	97.00%
Unfavorable Regulatory Action
Loss Contingencies [Line Items]
Liability for reductions and/or penalties from U.S Government audits	$ 179.9		$ 179.9		$ 168.6
Financial Standby Letter of Credit
Concentration Risk [Line Items]
Guarantor obligations, carrying value	9.3		9.3		6.3
Guarantor obligations, reduction to available borrowings			1		1.4
Guarantor obligations, facility						$ 15
Guarantor obligations, available amount	$ 6.7		$ 6.7		$ 10.1

Commitments and Contingencies_2

Commitments and Contingencies - Litigation (Details)	Sep. 05, 2017plaintiff	Jan. 09, 2017claim	Apr. 16, 2015claim	Sep. 30, 2018claim	Dec. 15, 2009claimplaintiff	Sep. 24, 2014claim	Sep. 23, 2014claim	Sep. 07, 2010claim	Jul. 02, 2010claim
Former stockholder litigation
Loss Contingencies [Line Items]
Loss contingencies, number of plaintiffs | plaintiff					6
Loss contingencies, new claims filed, number					9
Loss contingencies, claims amended, number						1		1	3
Loss contingencies, claims dismissed, number		1		3
Loss contingency, claims amended, number of claims consolidated						2	2
Loss contingencies, claims settled, number			1
Former stockholder litigation | United States District Court for Southern District of New York
Loss Contingencies [Line Items]
Loss contingencies, pending claims, number								3
United States District Court for the Eastern District of Virginia styled Langley v. Booz Allen Hamilton Holding Corp.
Loss Contingencies [Line Items]
Loss contingencies, number of plaintiffs | plaintiff	2