Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended
	Dec. 31, 2013	Jun. 30, 2014 Contract	Sep. 30, 2013
Schedule Of Summary Of Significant Accounting Policies [Line Items]
Percentage of ownership interest owned by parent		100.00%
Fee paid for waiver	$ 0	$ 175,000
Amount of waiver to maintain access to revolving credit facility		700,000
Waiver expiry date		May 02, 2014
Amount of new revolving credit facility agreement		45,000,000
Number of contracts		3
Maturity period of cash and cash equivalents		3 months
Intangible assets, net		1,181,000	2,040,000
Equity market information		There is no public market for Alion's redeemable common stock and therefore no observable price for its equity, individually or in the aggregate.
Benefit from decreased share redemption obligation		67,500,000
Redeemable common stock		61,031,000	61,895,000
Redeemable common stock, price per share		$ 8.1
Accounts Receivable [Member]
Schedule Of Summary Of Significant Accounting Policies [Line Items]
Percentage of receivables due from commercial customers		22.00%
Software [Member]
Schedule Of Summary Of Significant Accounting Policies [Line Items]
Intangible assets, amortization period		3 years
Secured Notes and Warrants [Member]
Schedule Of Summary Of Significant Accounting Policies [Line Items]
Maturity of debt		Nov. 01, 2014
Unsecured Notes [Member]
Schedule Of Summary Of Significant Accounting Policies [Line Items]
Maturity of debt		Feb. 01, 2015
Subsidiaries [Member]
Schedule Of Summary Of Significant Accounting Policies [Line Items]
Intangible assets, net		$ 1,200,000
Minimum [Member]
Schedule Of Summary Of Significant Accounting Policies [Line Items]
Percentage of income tax benefit		50.00%
Maximum [Member]
Schedule Of Summary Of Significant Accounting Policies [Line Items]
Intangible assets, amortization period		1 year 4 months 24 days
Equipment [Member]
Schedule Of Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, estimated useful lives		5 years

ALION SCIENCE & TECHNOLOGY CORP 10-Q