Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended		12 Months Ended	3 Months Ended		9 Months Ended		3 Months Ended			9 Months Ended	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended	3 Months Ended		9 Months Ended		3 Months Ended			9 Months Ended			3 Months Ended		9 Months Ended		12 Months Ended	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Dec. 28, 2012	Dec. 30, 2011	Dec. 28, 2012 operating_segments	Dec. 30, 2011	Dec. 28, 2012 NPS [Member] Segment As Reported [Member]	Dec. 30, 2011 NPS [Member] Segment As Reported [Member]	Dec. 28, 2012 NPS [Member] Segment As Reported [Member]	Dec. 30, 2011 NPS [Member] Segment As Reported [Member]		Dec. 28, 2012 NPS [Member] Segment Out of Period Adjustments Increase (Decrease) [Member]	Dec. 30, 2011 NPS [Member] Segment Out of Period Adjustments Increase (Decrease) [Member]	Dec. 28, 2012 NPS [Member] Segment Out of Period Adjustments Increase (Decrease) [Member]	Dec. 30, 2011 NPS [Member] Segment Out of Period Adjustments Increase (Decrease) [Member]	Mar. 30, 2012 NPS [Member] Segment Out of Period Adjustments Increase (Decrease) [Member]	Dec. 28, 2012 NPS [Member] Segment Adjusted [Member]	Dec. 30, 2011 NPS [Member] Segment Adjusted [Member]	Dec. 28, 2012 NPS [Member] Segment Adjusted [Member]	Dec. 30, 2011 NPS [Member] Segment Adjusted [Member]	Sep. 30, 2011 NPS [Member] Contracts Accounted for under Percentage of Completion, U.S. Claims [Member]	Dec. 28, 2012 NHS contract [Member] Contracts Accounted for under Percentage of Completion, U.S. Claims [Member]	Dec. 30, 2011 NHS contract [Member] Contracts Accounted for under Percentage of Completion, U.S. Claims [Member]	Dec. 30, 2011 NHS contract [Member] Contracts Accounted for under Percentage of Completion, U.S. Claims [Member]	Dec. 28, 2012 MSS [Member] Segment As Reported [Member]	Dec. 30, 2011 MSS [Member] Segment As Reported [Member]	Dec. 28, 2012 MSS [Member] Segment As Reported [Member]	Dec. 30, 2011 MSS [Member] Segment As Reported [Member]	Dec. 28, 2012 MSS [Member] Segment Out of Period Adjustments Increase (Decrease) [Member]	Dec. 30, 2011 MSS [Member] Segment Out of Period Adjustments Increase (Decrease) [Member]	Dec. 28, 2012 MSS [Member] Segment Out of Period Adjustments Increase (Decrease) [Member]	Dec. 30, 2011 MSS [Member] Segment Out of Period Adjustments Increase (Decrease) [Member]	Mar. 30, 2012 MSS [Member] Segment Out of Period Adjustments Increase (Decrease) [Member]	Dec. 28, 2012 MSS [Member] Segment Adjusted [Member]	Dec. 30, 2011 MSS [Member] Segment Adjusted [Member]	Dec. 28, 2012 MSS [Member] Segment Adjusted [Member]	Dec. 30, 2011 MSS [Member] Segment Adjusted [Member]	Dec. 28, 2012 BSS [Member] Segment As Reported [Member]	Dec. 30, 2011 BSS [Member] Segment As Reported [Member]		Dec. 28, 2012 BSS [Member] Segment As Reported [Member]	Dec. 30, 2011 BSS [Member] Segment As Reported [Member]		Dec. 28, 2012 BSS [Member] Segment Out of Period Adjustments Increase (Decrease) [Member]	Dec. 30, 2011 BSS [Member] Segment Out of Period Adjustments Increase (Decrease) [Member]	Dec. 28, 2012 BSS [Member] Segment Out of Period Adjustments Increase (Decrease) [Member]	Dec. 30, 2011 BSS [Member] Segment Out of Period Adjustments Increase (Decrease) [Member]	Mar. 30, 2012 BSS [Member] Segment Out of Period Adjustments Increase (Decrease) [Member]	Dec. 28, 2012 BSS [Member] Segment Adjusted [Member]	Dec. 30, 2011 BSS [Member] Segment Adjusted [Member]	Dec. 28, 2012 BSS [Member] Segment Adjusted [Member]	Dec. 30, 2011 BSS [Member] Segment Adjusted [Member]	Dec. 28, 2012 Corporate [Member]	Dec. 30, 2011 Corporate [Member]	Dec. 28, 2012 Corporate [Member]	Dec. 30, 2011 Corporate [Member]	Dec. 28, 2012 Eliminations [Member]	Dec. 30, 2011 Eliminations [Member]	Dec. 28, 2012 Eliminations [Member]	Dec. 30, 2011 Eliminations [Member]
Segment Reporting Information [Line Items]
Number of Operating Segments			3
Revenues	$ 3,781	$ 3,687	$ 11,434	$ 11,527	$ 1,340	$ 1,379	$ 4,083	$ 4,299	[1]	$ 0	$ (4)	$ 0	$ (4)	$ (5)	$ 1,340	$ 1,375	$ 4,083	$ 4,295					$ 1,620	$ 1,670	$ 4,838	$ 4,908	$ 1	$ (4)	$ 1	$ 0	$ (6)	$ 1,621	$ 1,666	$ 4,839	$ 4,908	$ 853	$ 663	[2]	$ 2,601	$ 2,410	[2]	$ 0	$ 53	$ 9	$ 44	$ (42)	$ 853	$ 716	$ 2,610	$ 2,454	$ 3	$ 3	$ 9	$ 9	$ (35)	$ (28)	$ (97)	$ (99)
Operating income (loss)	268	(1,307)	698	(1,251)	137	65	388	51	[1]	0	(5)	6	(2)	(10)	137	60	394	49					125	108	308	162	1	12	2	29	(33)	126	120	310	191	36	(1,459)	[2]	65	(1,417)	[2]	1	48	(10)	45	(45)	37	(1,411)	55	(1,372)	(30)	(21)	(63)	(47)	0	0	0	0
Depreciation and amortization	270	301	806	868	40	43	121	119	[1]	0	0	0	0		40	43	121	119					195	215	568	622	0	(1)	0	(2)		195	214	568	620	32	44	[2]	107	114	[2]	(4)	0	(2)	0		28	44	105	114	3	(1)	10	13	0	0	0	0
Change in accounting estimate, reduction in revenue																			42	204		204
Change in accounting estimate, reduction in operating income		$ 1,485																	$ 269		$ 1,485	$ 1,485

[1] The nine months ended December 30, 2011 amounts include $42 million reduction of revenue and $269 million reduction in operating income as a result of the settlement of claims with the U.S. government (see Note 18).

[2] The third quarter and nine months ended December 30, 2011 amounts include $204 million reduction of revenue and $1,485 million reduction in operating income as a result of the charge associated with the NHS contract (see Note 17).Ope