OTHER FINANCIAL DATA - EARNINGS PER SHARE (EPS) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Earnings attributable to common shares	$ 441	$ 353	[1]
Weighted-average common shares outstanding for basic EPS (in shares)	251,131,000	249,734,000	[1]
Vested RSUs included in basic WASO	600	555
Dilutive effect of stock options, restricted stock awards and restricted stock units (in shares)	1,115,000	1,753,000
Weighted-average common shares outstanding for diluted EPS (in shares)	252,246,000	251,487,000	[1]
Basic earnings per common share (in dollars per share)	$ 1.76	$ 1.41	[1]
Diluted earnings per common share (in dollars per share)	$ 1.75	$ 1.40	[1]
Antidilutive securities excluded from earnings per share	6,801	0
Performance-based RSUs [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Equity awards, granted (in shares)	424,360
Service-based RSUs [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Equity awards, granted (in shares)	92,413
IENova Plans [Member] | RSUs [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Equity awards, granted (in shares)	1,034,086

[1] As adjusted for the adoption of ASU 2016-09 as of January 1, 2016.