Other Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended												12 Months Ended										3 Months Ended			12 Months Ended
	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012		Oct. 31, 2011		Jul. 31, 2011		Apr. 30, 2011		Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011	Jan. 31, 2013 Government Investigations And Reviews	Jan. 31, 2013 Contract	Jan. 31, 2013 Potential Insurance Claims	Jan. 31, 2012 Potential Insurance Claims	Jan. 31, 2013 Standby Letters of Credit	Jan. 31, 2013 Performance Guarantee	Jan. 31, 2013 Bechtel SAIC Company, LLC	Jul. 31, 2012 DS and S	Oct. 31, 2012 DS and S	Mar. 31, 2006 DS and S	Jan. 31, 2013 Virnet X Inc
Other Commitments And Contingencies [Line Items]
Number of patents infringed																										2
Patents transferred and awarded													$ 80													$ 368
Percentage of proceeds obtained													25.00%
Aggregate loss provisions					308		232									15
Liability for estimate of loss																37
Ownership interest																						30.00%			50.00%
Gain on sale of interest in joint venture																							4
Amount to be paid in satisfaction of indemnification obligation																								4
Project financing from the company's provision of extended payment terms														100
Total project billings														220
Receivable due from VIE	53												53
Amount outstanding																				108
Surety bonds																					302
Revenues	2,711	2,870	2,828	2,764	2,471	[1]	2,790	[1]	2,573	[1]	2,663	[1]	11,173	10,497	10,798		481
Reduction in revenue																	2
Estimate of possible loss																		$ 30	$ 34

[1] Includes loss provisions of $232 million and $308 million recorded in the third quarter and fourth quarter, respectively, in connection with resolution of the CityTime matter described in Note 17.