SHAREOWNERS’ EQUITY - Redeemable Noncontrolling Interests (Narrative) (Details) - EUR (€) € in Millions	1 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Grid Technology Joint Venture | Scenario, Forecast
Redeemable Noncontrolling Interest [Line Items]
Amount to be paid to exercise redemption rights	€ 1,828
Renewable Energy Joint Venture | Scenario, Forecast
Redeemable Noncontrolling Interest [Line Items]
Amount to be paid to exercise redemption rights	€ 636
Grid Technology and Renewable Energy Joint Ventures
Redeemable Noncontrolling Interest [Line Items]
Annual accretion (as a percent)		3.00%
Nuclear and French Steam Power Joint Venture
Redeemable Noncontrolling Interest [Line Items]
Annual accretion (as a percent)		2.00%
Renewable Energy Joint Venture
Redeemable Noncontrolling Interest [Line Items]
Annual accretion (as a percent)		3.00%