OTHER FINANCIAL DATA - EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Earnings attributable to common shares	$ 57	$ 622	$ 757	$ 991
Weighted-average common shares outstanding for basic EPS (in shares)	251,692,000	250,386,000	251,425,000	250,073,000
Vested RSUs included in basic WASO	612,000	572,000	607,000	565,000
Dilutive effect of stock options, restricted stock awards and restricted stock units (in shares)	1,672,000	2,019,000	1,562,000	1,903,000
Weighted-average common shares outstanding for diluted EPS (in shares)	253,364,000	252,405,000	252,987,000	251,976,000
Basic earnings per common share (in dollars per share)	$ 0.23	$ 2.48	$ 3.01	$ 3.96
Diluted earnings per common share (in dollars per share)	$ 0.22	$ 2.46	$ 2.99	$ 3.93
Antidilutive securities excluded from earnings per share	2,608	0	2,608	2,426
Performance-based RSUs [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Equity awards, granted (in shares)	424,760
Service-based RSUs [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Equity awards, granted (in shares)	93,619
IENova Plans [Member] | RSUs [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Equity awards, granted (in shares)	1,043,709