Commitments, Contingencies and Other Items - Lawsuits (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012
Loss Contingencies
Estimated Litigation Liability	$ 306
Peruvian Tax Litigation | Pending or Threatened Litigation
Loss Contingencies
Loss Contingency, Asserted Claim	88
Peruvian Tax Litigation, Before Interest | Pending or Threatened Litigation
Loss Contingencies
Loss Contingency, Asserted Claim	26
Peruvian Tax Litigation, Income Taxwitholding 2001 and 2002 | Pending or Threatened Litigation
Loss Contingencies
Loss Contingency, Asserted Claim	3
Peruvian Tax Litigation, Disallowance of VAT in 2005 | Pending or Threatened Litigation
Loss Contingencies
Loss Contingency, Asserted Claim	16
Peruvian Tax Litigation, Vat for 2001 and 2002 | Pending or Threatened Litigation
Loss Contingencies
Loss Contingency, Asserted Claim	7
Employee Severance and Contractor Termination Disputes | Pending or Threatened Litigation
Loss Contingencies
Loss Contingency, Asserted Claim	41
Customer Bankruptcy Claim | Pending or Threatened Litigation
Loss Contingencies
Loss Contingency, Range of Possible Loss, Minimum	150
Loss Contingency, Range of Possible Loss, Maximum	450
Maximum | Brazilian Tax Claims | Pending or Threatened Litigation
Loss Contingencies
Loss Contingency, Range of Possible Loss, Portion Not Accrued	$ 57