Commitments, Contingencies and Other Items - Lawsuits (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2014	Sep. 30, 2014	Mar. 31, 2017
Loss Contingencies
Estimated Litigation Liability					$ 98
Peruvian Tax Litigation | Pending Litigation
Loss Contingencies
Loss Contingency, Asserted Claim					18
Release of Loss Contingency Accrual	$ 11	$ 15
Peruvian Tax Litigation, Before Interest | Pending Litigation
Loss Contingencies
Loss Contingency, Asserted Claim					26
Peruvian Tax Litigation, Income Tax witholding 2001 and 2002 | Pending Litigation
Loss Contingencies
Loss Contingency, Asserted Claim					3
Peruvian Tax Litigation, VAT for 2001 and 2002 | Pending Litigation
Loss Contingencies
Loss Contingency, Asserted Claim					7
Peruvian Tax Litigation, Disallowance of VAT in 2005 | Pending Litigation
Loss Contingencies
Loss Contingency, Asserted Claim					16
Employee Severance and Contractor Termination Disputes | Pending Litigation
Loss Contingencies
Loss Contingency, Asserted Claim					32
up to | Brazilian Tax Claims | Pending Litigation
Loss Contingencies
Loss Contingency, Range of Possible Loss, Portion Not Accrued					$ 51
Brazilian Tax Reserve Release [Member] | Brazilian Tax Claims | Pending Litigation
Loss Contingencies
Loss Contingency Accrual, Period Increase (Decrease)			$ 3	$ 6
Loss Contingency Accrual, Payments			$ 5