Retirement and Post-Retirement Benefit Plans (Details) (USD $) In Millions, unless otherwise specified						1 Months Ended	70 Months Ended					12 Months Ended
	Oct. 31, 2011	Oct. 31, 2010	Oct. 31, 2011 U.S. Defined Benefit Plans	Oct. 31, 2010 U.S. Defined Benefit Plans	Oct. 31, 2009 U.S. Defined Benefit Plans	Feb. 28, 2007 Post-Retirement Benefit Plans Year	Oct. 31, 2011 Post-Retirement Benefit Plans Year	Oct. 31, 2010 Post-Retirement Benefit Plans	Oct. 31, 2009 Post-Retirement Benefit Plans	Oct. 31, 2011 DPSP	Oct. 31, 2010 DPSP	Oct. 31, 2011 HP 401(k) Plan	Oct. 31, 2010 HP 401(k) Plan	Oct. 31, 2011 EDS 401(k) Plan through Dec 2010	Oct. 31, 2010 EDS 401(k) Plan through Dec 2010
Net pension and post-retirement benefit costs
Plan assets	$ 11,607	$ 10,354								$ 945	$ 927
Projected Benefit Obligation			11,945	10,902	10,034		816	845	992
Projected Benefit Obligation	$ 12,890	$ 11,829								$ 945	$ 927
Combination of age and years of service (in years)							62
Age for eligibility under HP Retirement Medical Savings Account Plan (in years)							45
Eligibility for Pre-2003 HP Retiree Medical Program limited to employees within period of satisfying criteria on June 30. 2007 (in years)						5
Percent of maximum matching contribution during the period (as a percent)													100.00%		100.00%
Percent of equal 401(k) match to employees effective during the period (as a percent)												100.00%		100.00%
Maximum percent 401(k) match to employees effective during the period (as a percent)												4.00%		4.00%