Acquisitions (Notes)	12 Months Ended
Dec. 31, 2013
Business Combinations [Abstract]
Acquisitions Disclosure [Text Block]	Acquisitions ALTA Systems, Inc.-On January 8, 2013, we completed the acquisition of ALTA Systems, Inc. (ALTA). The result of ALTA's operations have been included in our consolidated financial statements since that date. The acquisition was completed through a stock purchase agreement dated January 8, 2013, by and among ManTech International Corporation, ALTA Holdings LLC and the sole member of ALTA Holding LLC. ALTA is an information technology (IT) and professional services company with valuable applications in healthcare systems and capital planning. ALTA provides a broad range of IT and professional services to government and private industry in three major areas: capital planning and investment control; system design, development and operations; and fraud detection and statistical analysis. The acquisition allows ManTech to deliver technology services through ALTA's prime position on the Centers of Medicare and Medicaid Services (CMS) Enterprise Systems Development (ESD) contract. ManTech funded the acquisition with cash on hand. The stock purchase agreement did not contain provisions for contingent consideration. Revenues were $6.2 million and net income was $0.1 million for the period from January 8, 2013 to December 31, 2013. For the year ended December 31, 2013, ManTech incurred approximately $0.1 million of acquisition costs related to the ALTA transaction, which are included in the general and administrative expense in our consolidated statement of income and loss. The purchase price of $10.2 million was allocated to the underlying assets and liabilities based on their estimated fair value at the date of acquisition. We have recorded total assets of $11.1 million, including goodwill and intangible assets recognized in connection with the acquisition, and total liabilities of $0.9 million. Included in total assets were $0.7 million in acquisition related intangible assets. We recorded goodwill of $9.1 million, which will be deductible for tax purposes over 15 years, assuming adequate levels of taxable income. Recognition of goodwill is largely attributed to the value paid for ALTA's capabilities in providing technology services to the federal government in the health care sector. In allocating the purchase price, we considered among other factors, analysis of historical financial performance and estimates of future performance of ALTA's contracts. The components of other intangible assets associated with the acquisition were customer relationships and backlog valued at $0.6 million and $0.1 million, respectively. Customer contracts and related relationships represent the underlying relationships and agreements with ALTA's existing customers. Customer relationships and backlog are amortized straight-line over their estimated useful lives of approximately 20 years and 1 year, respectively. The weighted-average amortization period for the intangible assets is 17.1 years. HBGary, Inc.-On April 2, 2012, we completed the acquisition of certain assets of HBGary, Inc. (HBGary). The results of HBGary's operations have been included in our consolidated financial statements since that date. The acquisition was completed through an asset purchase agreement dated February 27, 2012, by and among a subsidiary of ManTech International Corporation, HBGary and the shareholders of HBGary. HBGary provides a comprehensive suite of software products to detect, analyze and diagnose Advance Persistent Threats and targeted malware. The company has customers in the financial services, energy, critical infrastructure and technology sectors. This acquisition broadened our cyber security solution capability for customers. ManTech funded the acquisition with cash on hand. The asset purchase agreement did not contain provisions for contingent consideration. Revenues were $3.2 million and net loss of $(3.2) million for the period from April 2, 2012 to December 31, 2012. For the year ended December 31, 2012, ManTech incurred approximately $0.8 million of acquisition costs related to the HBGary transaction, which are included in the general and administrative expense in our consolidated statement of income and loss. The purchase price of $23.8 million was allocated to the underlying assets and liabilities based on their fair value at the date of acquisition. Total assets were $24.6 million, including goodwill and intangible assets recognized in connection with the acquisition, and total liabilities were $0.8 million. Included in total assets were $3.1 million in acquisition related intangibles assets. We recorded goodwill of $20.1 million, which will be deductible for tax purposes over 15 years, assuming adequate levels of taxable income. Recognition of goodwill is largely attributed to the value paid for HBGary's capabilities in providing cyber service and product solutions to both federal and commercial customers. The components of other intangible assets associated with the acquisition were developed technology, customer relationships and trademark valued at $2.0 million, $0.9 million and $0.2 million, respectively. Developed technology represents the software developed by HBGary to detect, analyze and diagnose Advanced Persistent Threats and targeted malware. Customer relationship represent the underlying relationship with HBGary customers in the financial services, energy, critical infrastructure and technology sectors. Trademark represents the HBGary trade name that is recognized in the industry. Developed technology, customer relationships and trademark are amortized straight-line over their estimate useful lives of approximately 3 years, 2 years and 2 years, respectively. The weighted-average amortization period for the intangible assets is 2.5 years. Evolvent Technologies, Inc.-On January 6, 2012, we completed the acquisition of Evolvent Technologies, Inc. (Evolvent). The results of Evolvent's operations have been included in our consolidated financial statements since that date. The acquisition was completed through an equity purchase agreement dated January 6, 2012, by and among ManTech, shareholders and warrantholders of the parent of Evolvent, Evolvent and Prudent Management, LLC in its capacity as the sellers' representative. Evolvent provides services in clinical IT, clinical business intelligence, imaging cyber security, behavioral health, tele-health, software development and systems integration. Its systems and processes enable better decision-making at the point of care and full integration of medical information across different platforms. This acquisition has enabled ManTech to expand its customer relationships and deliver IT solutions through Evolvent's existing relationships with the Department of Defense health organizations, the Veterans Administration and the Department of Health and Human Services. ManTech funded the acquisition with cash on hand. The equity purchase agreement did not contain provisions for contingent consideration. Revenues were $27.9 million and net income was $0.3 million for the period from January 6, 2012 to December 31, 2012. For the year ended December 31, 2012, the Company incurred $0.2 million of acquisition costs associated with the Evolvent transaction, which are included in general and administrative expense in our consolidated statement of income and loss. The purchase price of $39.9 million was allocated to the underlying assets and liabilities based on their fair value at the date of acquisition. Total assets were $46.9 million, including goodwill and intangible assets recognized in connection with the acquisition, and total liabilities were $7.0 million. Included in total assets were $3.7 million in acquisition related intangible assets. We recorded goodwill of $33.2 million, which is not deductible for tax purposes. Recognition of goodwill is largely attributed to the highly skilled employees and the value paid for Evolvent's capabilities in providing IT services and solutions to the federal government healthcare sector. In allocating the purchase price, we considered among other factors, analyses of historical performance and estimates of future performance of Evolvent's contracts. The components of other intangible assets associated with the acquisition were customer relationships and backlog valued at $3.4 million and $0.3 million, respectively. Customer contracts and related relationships represent the underlying relationships and agreements with Evolvent's existing customers. Customer relationships and backlog are amortized over their estimated useful lives of 20 years and 1 year, respectively, using the pattern of benefits method. The weighted-average amortization period for the intangible assets is 18.5 years. Worldwide Information Network Systems, Inc.-On November 15, 2011, we completed the acquisition of Worldwide Information Network Systems, Inc. (WINS). The results of WINS' operations have been included in our consolidated financial statements since that date. The acquisition was completed through a stock purchase agreement dated October 26, 2011, by and among a subsidiary of ManTech International Corporation, WINS and its sole shareholder. WINS provides IT solutions with network engineering and cyber security technical expertise to the Department of Defense, Department of State and other agencies. WINS' largest customer is the Defense Intelligence Agency (DIA) through its prime position on the Solutions for the Information Technology Enterprise (SITE) Indefinite Delivery/Indefinite Quantity contract vehicle. This acquisition broadened our footprint in the high-end defense and intelligence market. The addition of WINS' IT capabilities, its prime position on the DIA SITE contract, support of the Department of State and other contracts will enhance our positioning with important customers and further our growth prospects. ManTech funded the acquisition with cash on hand. The stock purchase agreement did not contain provisions for contingent consideration. Revenues were $8.5 million and net income was $0.7 million for the period from November 15, 2011 to December 31, 2011. The Company incurred in fiscal year 2011 approximately $0.6 million of acquisition costs related to the WINS transaction, which are included in general and administrative expense in our consolidated statement of income and loss for the year ended December 31, 2011. The purchase price of $90.4 million was allocated to the underlying assets and liabilities based on their fair values at the date of acquisition. Total assets were $100.5 million, including goodwill and intangible assets recognized in connection with the acquisition, and total liabilities were $10.1 million. Included in total assets were $18.7 million in acquired intangible assets. We recorded goodwill of $62.5 million, which will be deductible for tax purposes over 15 years, assuming adequate levels of taxable income. Recognition of goodwill is largely attributed to the highly skilled employees and the value paid for WINS' capabilities in supporting high-end defense, intelligence and homeland security markets. In allocating the purchase price, we consider among other factors, analyses of historical financial performance and estimates of future performance of WINS' contracts. The components of other intangible assets associated with the acquisition were customer relationships and backlog valued at $18.0 million and $0.7 million, respectively. Customer contracts and related relationships represent the underlying relationships and agreements with WINS' existing customers. Customer relationships and backlog are amortized over their estimated useful lives of 20 years and 1 year, respectively, using the pattern of benefits method. The weighted-average amortization period for the intangible assets is 19.3 years. TranTech, Inc.-On February 11, 2011, we completed the acquisition of TranTech, Inc. (TranTech). The results of TranTech's operations have been included in our consolidated financial statements since that date. The acquisition was completed through a stock purchase agreement dated February 11, 2011, by and among ManTech International Corporation, TranTech and its sole shareholder. TranTech provides information technology, networking and cyber security services to the federal government. This acquisition allows us to continue extending our presence in the defense, security and intelligence communities, and to offer comprehensive solutions through a prime position on the Defense Information Systems Agency ENCORE II contract. ManTech funded the acquisition with cash on hand. The stock purchase agreement did not contain provisions for contingent consideration. Revenues were $12.5 million and net income was $0.9 million for the period from February 11, 2011 to December 31, 2011. The Company incurred in fiscal year 2011 approximately $0.3 million of acquisition costs related to the TranTech transaction, which are included in general and administrative expense in our consolidated statement of income and loss for the year ended December 31, 2011. The purchase price of $21.5 million was allocated to the underlying assets and liabilities based on their fair value at the date of acquisition. Total assets were $23.8 million, including goodwill and intangible assets recognized in connection with the acquisition, and total liabilities were $2.3 million. Included in total assets were $5.0 million in acquired intangible assets. We recorded goodwill of $14.6 million, which will be deductible for tax purposes over 15 years, assuming adequate levels of taxable income. Recognition of goodwill is largely attributed to the value paid for TranTech's capabilities in supporting high-end defense, intelligence and homeland security markets. In allocating the purchase price, we consider among other factors, analyses of historical financial performance and estimates of future performance of TranTech's contracts. The components of other intangible assets associated with the acquisition were customer relationships and backlog valued at $4.6 million and $0.4 million, respectively. Customer contracts and related relationships represent the underlying relationships and agreements with TranTech's existing customers. Customer relationships and backlog are amortized over their estimated useful lives of 20 years and 1 year, respectively, using the pattern of benefits method. The weighted-average amortization period for the intangibles assets is 18.5 years. Pro Forma Financial Information-We calculated the following unaudited pro forma amounts as if our acquisitions had occurred on January 1, 2012. Our consolidated pro forma revenue would have been $2,310.2 million and $2,591.9 million and our consolidated pro forma net income (loss) would have been $(6.0) million and $95.7 million for the years ended December 31, 2013 and 2012, respectively.

Acquisitions

ALTA Systems, Inc.-On January 8, 2013, we completed the acquisition of ALTA Systems, Inc. (ALTA). The result of ALTA's operations have been included in our consolidated financial statements since that date. The acquisition was completed through a stock purchase agreement dated January 8, 2013, by and among ManTech International Corporation, ALTA Holdings LLC and the sole member of ALTA Holding LLC. ALTA is an information technology (IT) and professional services company with valuable applications in healthcare systems and capital planning. ALTA provides a broad range of IT and professional services to government and private industry in three major areas: capital planning and investment control; system design, development and operations; and fraud detection and statistical analysis. The acquisition allows ManTech to deliver technology services through ALTA's prime position on the Centers of Medicare and Medicaid Services (CMS) Enterprise Systems Development (ESD) contract. ManTech funded the acquisition with cash on hand. The stock purchase agreement did not contain provisions for contingent consideration.

Revenues were $6.2 million and net income was $0.1 million for the period from January 8, 2013 to December 31, 2013. For the year ended December 31, 2013, ManTech incurred approximately $0.1 million of acquisition costs related to the ALTA transaction, which are included in the general and administrative expense in our consolidated statement of income and loss.

The purchase price of $10.2 million was allocated to the underlying assets and liabilities based on their estimated fair value at the date of acquisition. We have recorded total assets of $11.1 million, including goodwill and intangible assets recognized in connection with the acquisition, and total liabilities of $0.9 million. Included in total assets were $0.7 million in acquisition related intangible assets. We recorded goodwill of $9.1 million, which will be deductible for tax purposes over 15 years, assuming adequate levels of taxable income. Recognition of goodwill is largely attributed to the value paid for ALTA's capabilities in providing technology services to the federal government in the health care sector.

In allocating the purchase price, we considered among other factors, analysis of historical financial performance and estimates of future performance of ALTA's contracts. The components of other intangible assets associated with the acquisition were customer relationships and backlog valued at $0.6 million and $0.1 million, respectively. Customer contracts and related relationships represent the underlying relationships and agreements with ALTA's existing customers. Customer relationships and backlog are amortized straight-line over their estimated useful lives of approximately 20 years and 1 year, respectively. The weighted-average amortization period for the intangible assets is 17.1 years.

HBGary, Inc.-On April 2, 2012, we completed the acquisition of certain assets of HBGary, Inc. (HBGary). The results of HBGary's operations have been included in our consolidated financial statements since that date. The acquisition was completed through an asset purchase agreement dated February 27, 2012, by and among a subsidiary of ManTech International Corporation, HBGary and the shareholders of HBGary. HBGary provides a comprehensive suite of software products to detect, analyze and diagnose Advance Persistent Threats and targeted malware. The company has customers in the financial services, energy, critical infrastructure and technology sectors. This acquisition broadened our cyber security solution capability for customers. ManTech funded the acquisition with cash on hand. The asset purchase agreement did not contain provisions for contingent consideration.

Revenues were $3.2 million and net loss of $(3.2) million for the period from April 2, 2012 to December 31, 2012. For the year ended December 31, 2012, ManTech incurred approximately $0.8 million of acquisition costs related to the HBGary transaction, which are included in the general and administrative expense in our consolidated statement of income and loss.

The purchase price of $23.8 million was allocated to the underlying assets and liabilities based on their fair value at the date of acquisition. Total assets were $24.6 million, including goodwill and intangible assets recognized in connection with the acquisition, and total liabilities were $0.8 million. Included in total assets were $3.1 million in acquisition related intangibles assets. We recorded goodwill of $20.1 million, which will be deductible for tax purposes over 15 years, assuming adequate levels of taxable income. Recognition of goodwill is largely attributed to the value paid for HBGary's capabilities in providing cyber service and product solutions to both federal and commercial customers.

The components of other intangible assets associated with the acquisition were developed technology, customer relationships and trademark valued at $2.0 million, $0.9 million and $0.2 million, respectively. Developed technology represents the software developed by HBGary to detect, analyze and diagnose Advanced Persistent Threats and targeted malware. Customer relationship represent the underlying relationship with HBGary customers in the financial services, energy, critical infrastructure and technology sectors. Trademark represents the HBGary trade name that is recognized in the industry. Developed technology, customer relationships and trademark are amortized straight-line over their estimate useful lives of approximately 3 years, 2 years and 2 years, respectively. The weighted-average amortization period for the intangible assets is 2.5 years.

Evolvent Technologies, Inc.-On January 6, 2012, we completed the acquisition of Evolvent Technologies, Inc. (Evolvent). The results of Evolvent's operations have been included in our consolidated financial statements since that date. The acquisition was completed through an equity purchase agreement dated January 6, 2012, by and among ManTech, shareholders and warrantholders of the parent of Evolvent, Evolvent and Prudent Management, LLC in its capacity as the sellers' representative. Evolvent provides services in clinical IT, clinical business intelligence, imaging cyber security, behavioral health, tele-health, software development and systems integration. Its systems and processes enable better decision-making at the point of care and full integration of medical information across different platforms. This acquisition has enabled ManTech to expand its customer relationships and deliver IT solutions through Evolvent's existing relationships with the Department of Defense health organizations, the Veterans Administration and the Department of Health and Human Services. ManTech funded the acquisition with cash on hand. The equity purchase agreement did not contain provisions for contingent consideration.

Revenues were $27.9 million and net income was $0.3 million for the period from January 6, 2012 to December 31, 2012. For the year ended December 31, 2012, the Company incurred $0.2 million of acquisition costs associated with the Evolvent transaction, which are included in general and administrative expense in our consolidated statement of income and loss.

The purchase price of $39.9 million was allocated to the underlying assets and liabilities based on their fair value at the date of acquisition. Total assets were $46.9 million, including goodwill and intangible assets recognized in connection with the acquisition, and total liabilities were $7.0 million. Included in total assets were $3.7 million in acquisition related intangible assets. We recorded goodwill of $33.2 million, which is not deductible for tax purposes. Recognition of goodwill is largely attributed to the highly skilled employees and the value paid for Evolvent's capabilities in providing IT services and solutions to the federal government healthcare sector.

In allocating the purchase price, we considered among other factors, analyses of historical performance and estimates of future performance of Evolvent's contracts. The components of other intangible assets associated with the acquisition were customer relationships and backlog valued at $3.4 million and $0.3 million, respectively. Customer contracts and related relationships represent the underlying relationships and agreements with Evolvent's existing customers. Customer relationships and backlog are amortized over their estimated useful lives of 20 years and 1 year, respectively, using the pattern of benefits method. The weighted-average amortization period for the intangible assets is 18.5 years.

Worldwide Information Network Systems, Inc.-On November 15, 2011, we completed the acquisition of Worldwide Information Network Systems, Inc. (WINS). The results of WINS' operations have been included in our consolidated financial statements since that date. The acquisition was completed through a stock purchase agreement dated October 26, 2011, by and among a subsidiary of ManTech International Corporation, WINS and its sole shareholder. WINS provides IT solutions with network engineering and cyber security technical expertise to the Department of Defense, Department of State and other agencies. WINS' largest customer is the Defense Intelligence Agency (DIA) through its prime position on the Solutions for the Information Technology Enterprise (SITE) Indefinite Delivery/Indefinite Quantity contract vehicle. This acquisition broadened our footprint in the high-end defense and intelligence market. The addition of WINS' IT capabilities, its prime position on the DIA SITE contract, support of the Department of State and other contracts will enhance our positioning with important customers and further our growth prospects. ManTech funded the acquisition with cash on hand. The stock purchase agreement did not contain provisions for contingent consideration.

Revenues were $8.5 million and net income was $0.7 million for the period from November 15, 2011 to December 31, 2011. The Company incurred in fiscal year 2011 approximately $0.6 million of acquisition costs related to the WINS transaction, which are included in general and administrative expense in our consolidated statement of income and loss for the year ended December 31, 2011.

The purchase price of $90.4 million was allocated to the underlying assets and liabilities based on their fair values at the date of acquisition. Total assets were $100.5 million, including goodwill and intangible assets recognized in connection with the acquisition, and total liabilities were $10.1 million. Included in total assets were $18.7 million in acquired intangible assets. We recorded goodwill of $62.5 million, which will be deductible for tax purposes over 15 years, assuming adequate levels of taxable income. Recognition of goodwill is largely attributed to the highly skilled employees and the value paid for WINS' capabilities in supporting high-end defense, intelligence and homeland security markets.

In allocating the purchase price, we consider among other factors, analyses of historical financial performance and estimates of future performance of WINS' contracts. The components of other intangible assets associated with the acquisition were customer relationships and backlog valued at $18.0 million and $0.7 million, respectively. Customer contracts and related relationships represent the underlying relationships and agreements with WINS' existing customers. Customer relationships and backlog are amortized over their estimated useful lives of 20 years and 1 year, respectively, using the pattern of benefits method. The weighted-average amortization period for the intangible assets is 19.3 years.

TranTech, Inc.-On February 11, 2011, we completed the acquisition of TranTech, Inc. (TranTech). The results of TranTech's operations have been included in our consolidated financial statements since that date. The acquisition was completed through a stock purchase agreement dated February 11, 2011, by and among ManTech International Corporation, TranTech and its sole shareholder. TranTech provides information technology, networking and cyber security services to the federal government. This acquisition allows us to continue extending our presence in the defense, security and intelligence communities, and to offer comprehensive solutions through a prime position on the Defense Information Systems Agency ENCORE II contract. ManTech funded the acquisition with cash on hand. The stock purchase agreement did not contain provisions for contingent consideration.

Revenues were $12.5 million and net income was $0.9 million for the period from February 11, 2011 to December 31, 2011. The Company incurred in fiscal year 2011 approximately $0.3 million of acquisition costs related to the TranTech transaction, which are included in general and administrative expense in our consolidated statement of income and loss for the year ended December 31, 2011.

The purchase price of $21.5 million was allocated to the underlying assets and liabilities based on their fair value at the date of acquisition. Total assets were $23.8 million, including goodwill and intangible assets recognized in connection with the acquisition, and total liabilities were $2.3 million. Included in total assets were $5.0 million in acquired intangible assets. We recorded goodwill of $14.6 million, which will be deductible for tax purposes over 15 years, assuming adequate levels of taxable income. Recognition of goodwill is largely attributed to the value paid for TranTech's capabilities in supporting high-end defense, intelligence and homeland security markets.

In allocating the purchase price, we consider among other factors, analyses of historical financial performance and estimates of future performance of TranTech's contracts. The components of other intangible assets associated with the acquisition were customer relationships and backlog valued at $4.6 million and $0.4 million, respectively. Customer contracts and related relationships represent the underlying relationships and agreements with TranTech's existing customers. Customer relationships and backlog are amortized over their estimated useful lives of 20 years and 1 year, respectively, using the pattern of benefits method. The weighted-average amortization period for the intangibles assets is 18.5 years.

Pro Forma Financial Information-We calculated the following unaudited pro forma amounts as if our acquisitions had occurred on January 1, 2012. Our consolidated pro forma revenue would have been $2,310.2 million and $2,591.9 million and our consolidated pro forma net income (loss) would have been $(6.0) million and $95.7 million for the years ended December 31, 2013 and 2012, respectively.