Summary of Significnat Accounting Policies (Policies)	12 Months Ended
Dec. 31, 2011
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation-Our consolidated financial statements include the accounts of ManTech International Corporation, wholly-owned subsidiaries and other entities, which we control. Our share of affiliates' earnings (losses) that we do not control is included in our consolidated statements of income using the equity method. All inter-company accounts and transactions have been eliminated. We determine whether we have a controlling financial interest in a Variable Interest Entity (VIE). The reporting entity with a variable interest or interest that provide the reporting entity with a controlling financial interest in a VIE will have both (a) the power to direct the activities of a VIE that most significantly impact the VIE's economic performance and (b) the obligation to absorb losses of the VIE that could potentially be significant to the VIE or the right to receive benefits from the VIE that could potentially be significant to the VIE. We have one entity that has been consolidated as a VIE. The purpose of the entity is to perform on certain U.S. Navy contracts. The maximum amount of loss we are exposed to as of December 31, 2011 was not material to our consolidated financial statements.
Use of Accounting Estimates	Use of Accounting Estimates-We prepare our consolidated financial statements in conformity with accounting principles generally accepted in the United States of America, which require management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates involve judgments with respect to, among other things, various future economic factors that are difficult to predict and are beyond the control of the Company. Therefore, actual amounts could differ from these estimates.
Revenue Recognition	Revenue Recognition-We derive the majority of our revenues from cost-plus-fixed-fee, cost-plus-award-fee, firm-fixed-price or time-and-materials contracts. Revenues for cost-reimbursable contracts are recorded as reimbursable costs are incurred, including an estimated share of the applicable contractual fees earned. For performance-based fees under cost-reimbursable contracts, that are subject to the provisions of ASC 605-35, Construction-Type and Certain Production-Type Contracts, we recognize the relevant portion of the expected fee to be awarded by the client at the time such fee can be reasonably estimated, based on factors such as our prior award experience and communications with the client regarding performance. For cost-reimbursable contracts with performance-based fee incentives that are subject to the provisions of SEC Topic 13, Revenue Recognition, we recognize the relevant portion of the fee upon customer approval. For time-and-materials contracts, revenues are recognized to the extent of billable rates times hours delivered plus materials and other reimbursable costs incurred. For long-term fixed-price production contracts, revenues are recognized at a rate per unit as the units are delivered or by other methods to measure services provided. Revenues from other long-term fixed-price contracts are recognized ratably over the contract period or by other appropriate methods to measure services provided. Contract costs are expensed as incurred except for certain limited long-term contracts noted below. For long-term contracts, specifically described in the scope section of ASC 605-35, we apply the percentage of completion method. Under the percentage of completion method, income is recognized at a consistent profit margin over the period of performance based on estimated profit margins at completion of the contract. This method of accounting requires estimating the total revenues and total contract cost at completion of the contract. During the performance of long-term contracts, these estimates are periodically reviewed and revisions are made as required using the cumulative catch-up method of accounting. The impact on revenues and contract profit as a result of these revisions is included in the periods in which the revisions are made. This method can result in the deferral of costs or the deferral of profit on these contracts. Because we assume the risk of performing a fixed-price contract at a set price, the failure to accurately estimate ultimate costs or to control costs during performance of the work could result, and in some instances has resulted, in reduced profits or losses for such contracts. Both the individual changes in contract estimates and aggregate net changes in contract estimates recognized using the cumulative catch-up method of accounting were not material to the consolidated statement of operations for all periods presented. Estimated losses on contracts at completion are recognized when identified. In certain circumstances, revenues are recognized when contract amendments have not been finalized.
Cost of Services	Cost of Services-Cost of services consists primarily of compensation expenses for program personnel, the fringe benefits associated with this compensation and other direct expenses incurred to complete programs, including cost of materials and subcontract efforts.
Cash and Cash Equivalents	Cash and Cash Equivalents-For the purpose of reporting cash flows, cash and cash equivalents include cash on hand, amounts due from banks and short-term investments with maturity dates of three months or less at the date of purchase. Due to the short maturity of cash equivalents, the carrying value on our consolidated balance sheets approximates fair value.
Property and Equipment	Property and Equipment-Property and equipment are recorded at original cost. Upon sale or retirement, the costs and related accumulated depreciation or amortization are eliminated from the respective accounts and any resulting gain or loss is included in income. Maintenance and repairs are charged to expense as incurred.
Depreciation and Amortization	Depreciation and Amortization-Furniture and office equipment are depreciated using the straight-line method with estimated useful lives ranging from one to seven years. Leasehold improvements are amortized using the straight-line method over the term of the lease.
Inventory	Inventory-Inventory is included in prepaid expenses and other on our consolidated balance sheets and is carried at the lower of cost or market. Cost is computed on a specific identification basis.
Goodwill and Other Intangibles-net	Goodwill and Other Intangibles-net-Goodwill represents the excess of cost over the fair value of net tangible and identifiable intangible assets of acquired companies. Contract rights and other intangibles are amortized primarily using the pattern of benefits method over periods ranging from one to twenty-five years. We accounted for the cost of computer software developed or obtained for internal use in accordance with ASC 350-985, Software. These capitalized software costs are included in other intangibles, net.
Software Development Costs	Software Development Costs-We account for software development costs related to software products for sale, lease or otherwise marketed in accordance with ASC 985-20, Costs of Software to be Sold, Leased, or Marketed. For projects fully funded by us, development costs are capitalized from the point of demonstrated technological feasibility until the point in time that the product is available for general release to customers. Once the product is available for general release, capitalized costs are amortized based on units sold or on a straight-line basis over a five-year period or other such shorter period as may be required. We recorded $0, $0.2 million and $0.1 million per year of amortization expense on capitalized software cost for sale for the years ended December 31, 2011, 2010 and 2009, respectively. Amortization expense for the years ended December 31, 2010 and 2009 included a write down of an acquisition related intangible asset for internally developed software of $0.1 million and less than $0.1 million, respectively. The write downs were based on changes in the estimated net realizable value of the asset. There were no capitalized software costs for sale included in other intangibles, net at December 31, 2011 and 2010.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets-Whenever events or changes in circumstances indicate that the carrying amount of long-lived assets may not be fully recoverable, we evaluate the probability that future undiscounted net cash flows, without interest charges, will be less than the carrying amount of the assets. If any impairment were indicated as a result of this review, we would recognize a loss based on the amount by which the carrying amount exceeds the estimated fair value. We review goodwill at least annually for impairment. We have elected to perform this review annually during the second quarter of each calendar year. No adjustments were necessary as a result of this review during the quarter ended June 30, 2011.
Employee Supplemental Savings Plan Assets	Employee Supplemental Savings Plan Assets-We maintain several non-qualified defined contribution supplemental retirement plans for certain key employees that are accounted for in accordance with ASC 710-10-05, Deferred Compensation - Rabbi Trusts, as the underlying assets are held in rabbi trusts with investments directed by the respective employee. A rabbi trust is a grantor trust generally set up to fund compensation for a select group of management and the assets of this trust are available to satisfy the claims of general creditors in the event of bankruptcy of the Company. The assets held by the rabbi trusts are recorded at cash surrender value in our consolidated financial statements as Employee Supplemental Savings Plan assets with a related liability to employees recorded as a deferred compensation liability in accrued retirement.
Billings In Excess of Revenue Earned	Billings In Excess of Revenue Earned-We receive advances and milestone payments from customers that exceed the revenues earned to date. We classify such items as current liabilities.
Stock-based Compensation	Stock-based Compensation-We account for stock-based compensation in accordance with ASC 718, Compensation - Stock Compensation. ASC 718 requires the use of a valuation model to calculate the fair value of stock-based awards. We have elected to use the Black-Scholes-Merton pricing model to determine fair value on the dates of grant. The fair value is included in operating expenses or capitalized, as appropriate, straight-line over the period in which service is provided in exchange for the award. See Note 10 for further discussion regarding stock-based compensation.
Income Taxes	Income Taxes-We account for income taxes in accordance with ASC 740, Income Taxes. Under this method, deferred income taxes are determined based on the estimated future tax effects of differences between the financial statement and tax bases of assets and liabilities given the provisions of enacted tax laws. Deferred income tax provisions and benefits are based on changes to the assets or liabilities from year-to-year. In providing for deferred taxes, we consider tax regulations of the jurisdictions in which we operate, estimates of future taxable income and available tax planning strategies. If tax regulations, operating results or the ability to implement tax-planning strategies vary, adjustments to the carrying value of deferred tax assets and liabilities may be required. Valuation allowances are recorded related to deferred tax assets based on the “more likely than not” criteria. We recognize the financial statement benefit of a tax position only after determining that the relevant tax authority would “more likely than not” sustain the position following an audit. For tax positions meeting the “more likely than not” threshold, the amount recognized in the financial statements is the largest benefit that has a greater than 50 percent likelihood of being realized upon ultimate settlement with the relevant tax authority.
Foreign-Currency Translation	Foreign-Currency Translation-All assets and liabilities of foreign subsidiaries are translated into U.S. dollars at fiscal year-end exchange rates. Income and expense items are translated at average monthly exchange rates prevailing during the fiscal year. The resulting translation adjustments are recorded as a component of accumulated other comprehensive income (loss).
Comprehensive Income, Policy	Comprehensive Income-Comprehensive income is presented in our consolidated statements of changes in stockholders' equity. Comprehensive income consists of net income; translation adjustments, net of tax; and actuarial gain (loss) on defined benefit pension plan, net of tax.
Fair Value of Financial Instruments	Fair Value of Financial Instruments-The carrying value of our cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate their fair values.

Summary of Significnat Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2011

Principles of Consolidation-Our consolidated financial statements include the accounts of ManTech International Corporation, wholly-owned subsidiaries and other entities, which we control. Our share of affiliates' earnings (losses) that we do not control is included in our consolidated statements of income using the equity method. All inter-company accounts and transactions have been eliminated.

We determine whether we have a controlling financial interest in a Variable Interest Entity (VIE). The reporting entity with a variable interest or interest that provide the reporting entity with a controlling financial interest in a VIE will have both (a) the power to direct the activities of a VIE that most significantly impact the VIE's economic performance and (b) the obligation to absorb losses of the VIE that could potentially be significant to the VIE or the right to receive benefits from the VIE that could potentially be significant to the VIE.

We have one entity that has been consolidated as a VIE. The purpose of the entity is to perform on certain U.S. Navy contracts. The maximum amount of loss we are exposed to as of December 31, 2011 was not material to our consolidated financial statements.

Use of Accounting Estimates

Use of Accounting Estimates-We prepare our consolidated financial statements in conformity with accounting principles generally accepted in the United States of America, which require management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates involve judgments with respect to, among other things, various future economic factors that are difficult to predict and are beyond the control of the Company. Therefore, actual amounts could differ from these estimates.

Revenue Recognition

Revenue Recognition-We derive the majority of our revenues from cost-plus-fixed-fee, cost-plus-award-fee, firm-fixed-price or time-and-materials contracts. Revenues for cost-reimbursable contracts are recorded as reimbursable costs are incurred, including an estimated share of the applicable contractual fees earned. For performance-based fees under cost-reimbursable contracts, that are subject to the provisions of ASC 605-35, Construction-Type and Certain Production-Type Contracts, we recognize the relevant portion of the expected fee to be awarded by the client at the time such fee can be reasonably estimated, based on factors such as our prior award experience and communications with the client regarding performance. For cost-reimbursable contracts with performance-based fee incentives that are subject to the provisions of SEC Topic 13, Revenue Recognition, we recognize the relevant portion of the fee upon customer approval. For time-and-materials contracts, revenues are recognized to the extent of billable rates times hours delivered plus materials and other reimbursable costs incurred. For long-term fixed-price production contracts, revenues are recognized at a rate per unit as the units are delivered or by other methods to measure services provided. Revenues from other long-term fixed-price contracts are recognized ratably over the contract period or by other appropriate methods to measure services provided. Contract costs are expensed as incurred except for certain limited long-term contracts noted below. For long-term contracts, specifically described in the scope section of ASC 605-35, we apply the percentage of completion method. Under the percentage of completion method, income is recognized at a consistent profit margin over the period of performance based on estimated profit margins at completion of the contract. This method of accounting requires estimating the total revenues and total contract cost at completion of the contract. During the performance of long-term contracts, these estimates are periodically reviewed and revisions are made as required using the cumulative catch-up method of accounting. The impact on revenues and contract profit as a result of these revisions is included in the periods in which the revisions are made. This method can result in the deferral of costs or the deferral of profit on these contracts. Because we assume the risk of performing a fixed-price contract at a set price, the failure to accurately estimate ultimate costs or to control costs during performance of the work could result, and in some instances has resulted, in reduced profits or losses for such contracts. Both the individual changes in contract estimates and aggregate net changes in contract estimates recognized using the cumulative catch-up method of accounting were not material to the consolidated statement of operations for all periods presented. Estimated losses on contracts at completion are recognized when identified. In certain circumstances, revenues are recognized when contract amendments have not been finalized.

Cost of Services

Cost of Services-Cost of services consists primarily of compensation expenses for program personnel, the fringe benefits associated with this compensation and other direct expenses incurred to complete programs, including cost of materials and subcontract efforts.

Cash and Cash Equivalents

Cash and Cash Equivalents-For the purpose of reporting cash flows, cash and cash equivalents include cash on hand, amounts due from banks and short-term investments with maturity dates of three months or less at the date of purchase. Due to the short maturity of cash equivalents, the carrying value on our consolidated balance sheets approximates fair value.

Property and Equipment

Property and Equipment-Property and equipment are recorded at original cost. Upon sale or retirement, the costs and related accumulated depreciation or amortization are eliminated from the respective accounts and any resulting gain or loss is included in income. Maintenance and repairs are charged to expense as incurred.

Depreciation and Amortization

Depreciation and Amortization-Furniture and office equipment are depreciated using the straight-line method with estimated useful lives ranging from one to seven years. Leasehold improvements are amortized using the straight-line method over the term of the lease.

Inventory

Inventory-Inventory is included in prepaid expenses and other on our consolidated balance sheets and is carried at the lower of cost or market. Cost is computed on a specific identification basis.

Goodwill and Other Intangibles-net

Goodwill and Other Intangibles-net-Goodwill represents the excess of cost over the fair value of net tangible and identifiable intangible assets of acquired companies. Contract rights and other intangibles are amortized primarily using the pattern of benefits method over periods ranging from one to twenty-five years.

We accounted for the cost of computer software developed or obtained for internal use in accordance with ASC 350-985, Software. These capitalized software costs are included in other intangibles, net.

Software Development Costs

Software Development Costs-We account for software development costs related to software products for sale, lease or otherwise marketed in accordance with ASC 985-20, Costs of Software to be Sold, Leased, or Marketed. For projects fully funded by us, development costs are capitalized from the point of demonstrated technological feasibility until the point in time that the product is available for general release to customers. Once the product is available for general release, capitalized costs are amortized based on units sold or on a straight-line basis over a five-year period or other such shorter period as may be required. We recorded $0, $0.2 million and $0.1 million per year of amortization expense on capitalized software cost for sale for the years ended December 31, 2011, 2010 and 2009, respectively. Amortization expense for the years ended December 31, 2010 and 2009 included a write down of an acquisition related intangible asset for internally developed software of $0.1 million and less than $0.1 million, respectively. The write downs were based on changes in the estimated net realizable value of the asset. There were no capitalized software costs for sale included in other intangibles, net at December 31, 2011 and 2010.

Impairment of Long-Lived Assets

Impairment of Long-Lived Assets-Whenever events or changes in circumstances indicate that the carrying amount of long-lived assets may not be fully recoverable, we evaluate the probability that future undiscounted net cash flows, without interest charges, will be less than the carrying amount of the assets. If any impairment were indicated as a result of this review, we would recognize a loss based on the amount by which the carrying amount exceeds the estimated fair value.

We review goodwill at least annually for impairment. We have elected to perform this review annually during the second quarter of each calendar year. No adjustments were necessary as a result of this review during the quarter ended June 30, 2011.

Employee Supplemental Savings Plan Assets

Employee Supplemental Savings Plan Assets-We maintain several non-qualified defined contribution supplemental retirement plans for certain key employees that are accounted for in accordance with ASC 710-10-05, Deferred Compensation - Rabbi Trusts, as the underlying assets are held in rabbi trusts with investments directed by the respective employee. A rabbi trust is a grantor trust generally set up to fund compensation for a select group of management and the assets of this trust are available to satisfy the claims of general creditors in the event of bankruptcy of the Company. The assets held by the rabbi trusts are recorded at cash surrender value in our consolidated financial statements as Employee Supplemental Savings Plan assets with a related liability to employees recorded as a deferred compensation liability in accrued retirement.

Billings In Excess of Revenue Earned

Billings In Excess of Revenue Earned-We receive advances and milestone payments from customers that exceed the revenues earned to date. We classify such items as current liabilities.

Stock-based Compensation

Stock-based Compensation-We account for stock-based compensation in accordance with ASC 718, Compensation - Stock Compensation. ASC 718 requires the use of a valuation model to calculate the fair value of stock-based awards. We have elected to use the Black-Scholes-Merton pricing model to determine fair value on the dates of grant. The fair value is included in operating expenses or capitalized, as appropriate, straight-line over the period in which service is provided in exchange for the award. See Note 10 for further discussion regarding stock-based compensation.

Income Taxes

Income Taxes-We account for income taxes in accordance with ASC 740, Income Taxes. Under this method, deferred income taxes are determined based on the estimated future tax effects of differences between the financial statement and tax bases of assets and liabilities given the provisions of enacted tax laws. Deferred income tax provisions and benefits are based on changes to the assets or liabilities from year-to-year. In providing for deferred taxes, we consider tax regulations of the jurisdictions in which we operate, estimates of future taxable income and available tax planning strategies. If tax regulations, operating results or the ability to implement tax-planning strategies vary, adjustments to the carrying value of deferred tax assets and liabilities may be required. Valuation allowances are recorded related to deferred tax assets based on the “more likely than not” criteria.

We recognize the financial statement benefit of a tax position only after determining that the relevant tax authority would “more likely than not” sustain the position following an audit. For tax positions meeting the “more likely than not” threshold, the amount recognized in the financial statements is the largest benefit that has a greater than 50 percent likelihood of being realized upon ultimate settlement with the relevant tax authority.

Foreign-Currency Translation

Foreign-Currency Translation-All assets and liabilities of foreign subsidiaries are translated into U.S. dollars at fiscal year-end exchange rates. Income and expense items are translated at average monthly exchange rates prevailing during the fiscal year. The resulting translation adjustments are recorded as a component of accumulated other comprehensive income (loss).

Comprehensive Income, Policy

Comprehensive Income-Comprehensive income is presented in our consolidated statements of changes in stockholders' equity. Comprehensive income consists of net income; translation adjustments, net of tax; and actuarial gain (loss) on defined benefit pension plan, net of tax.

Fair Value of Financial Instruments

Fair Value of Financial Instruments-The carrying value of our cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate their fair values.