REVENUES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenues	$ 56,771	$ 40,786
Private Equity
Disclosure of disaggregation of revenue from contracts with customers [line items]
Revenues	36,828	$ 24,220
Construction Services [Member] \| Private Equity
Disclosure of disaggregation of revenue from contracts with customers [line items]
Transaction price allocated to remaining performance obligations	$ 8,000
Backlog	P2Y
Service concession arrangements [member] \| Brazilian water and wastewater services [Member] \| Private Equity
Disclosure of disaggregation of revenue from contracts with customers [line items]
Backlog	P25Y

The income arising in the course of an entity's ordinary activities. Income is increases in economic benefits during the accounting period in the form of inflows or enhancements of assets or decreases of liabilities that result in an increase in equity, other than those relating to contributions from equity participants.

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+ Details