Commitments, Contingencies and Other Items - Lawsuits (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) Employee contract
Loss Contingencies
Estimated litigation liability	$ 92
Peruvian Tax Litigation, Before Interest | Pending Litigation
Loss Contingencies
Asserted claim	26
Peruvian Tax Litigation | Pending Litigation
Loss Contingencies
Asserted claim	14
Employee Severance and Contractor Termination Disputes | Pending Litigation
Loss Contingencies
Asserted claim	32
Brazilian Tax Claims
Loss Contingencies
Loss Contingency, Estimate of Possible Loss	$ 54
United States of America ex rel., Stephen Bishop v. Level 3 Communications, Inc. et al.
Loss Contingencies
Number of former employees names in lawsuit | Employee	2
Number of government contracts in question | contract	2
Damages sought, value	$ 50