EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator (basic and diluted):
Net income	$ 1,721	$ 1,652	$ 1,045
Less: Preferred stock dividends	29	14	14
Net income available to common stockholders	$ 1,692	$ 1,638	$ 1,031
Denominator:
Weighted-average common shares outstanding - basic (in shares)	478,822,072	502,157,440	522,093,545
Dilutive common shares: share-based awards (in shares)	1,608,669	1,527,651	1,837,173
Weighted-average common shares outstanding - diluted (in shares)	480,430,741	503,685,091	523,930,718
Earnings per common share:
Basic (in dollars per share)	$ 3.54	$ 3.26	$ 1.97
Diluted (in dollars per share)	$ 3.52	$ 3.25	$ 1.97
Antidilutive securities (in shares)	0	533	0