QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Quarterly Disclosures) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 5,041	$ 4,310	$ 3,711	$ 3,341	$ 4,377	$ 3,877	$ 3,334	$ 3,242	$ 16,403	$ 14,830	$ 14,607
Operating income (loss)	1,467	917	669	580	703	359	18	(3,872)	3,633	(2,792)	(13,512)
Net (loss) income from continuing operations	1,193	242	326	268	202	292	(229)	(4,097)	2,029	(3,832)	(12,180)
Net income (loss) from discontinued operations	16	3	9	38	(2)	(6)	(181)	(4)	66	(193)	91
Net income	1,209	245	335	306	200	286	(410)	(4,101)	2,095	(4,025)	(12,089)
Net loss (income) and preferred dividends attributable to noncontrolling interests	(168)	35	(66)	(75)	111	(47)	(57)	(73)	(274)	(66)
Net income from discontinued operations attributable to noncontrolling interests	0	0	(1)	(3)	(19)	(22)	(12)	(10)	(4)	(63)	(79)
Net income (loss) attributable to common stockholders	$ 1,041	$ 280	$ 268	$ 228	$ 292	$ 217	$ (479)	$ (4,184)	$ 1,817	$ (4,154)	$ (12,236)
Continuing operations (in dollars per share)					$ 0.22	$ 0.18	$ (0.23)	$ (3.34)	$ 1.21	$ (2.96)	$ (11.32)
Discontinued operations (in dollars per share)	$ 0.01	$ 0.00	$ 0.00	$ 0.03	(0.01)	(0.02)	(0.15)	(0.01)	0.04	(0.20)	0.01
Earnings Per Share, Diluted	$ 0.71	$ 0.19	$ 0.18	$ 0.16					1.25
Earnings per share, basic and diluted (in dollars per share)					$ 0.21	$ 0.16	$ (0.38)	$ (3.35)	$ 1.25	$ (3.16)	$ (11.31)
Weighted Average Number of Shares Outstanding, Basic	1,448,000,000	1,448,000,000	1,447,000,000	1,446,000,000	1,403,000,000	1,346,000,000	1,269,000,000	1,251,000,000	1,447,000,000	1,318,000,000	1,082,000,000
Weighted Average Number of Shares Outstanding, Diluted	1,455,000,000.00	1,454,000,000.00	1,453,000,000.00	1,454,000,000.00	1,410,000,000	1,351,000,000	1,269,000,000	1,251,000,000	1,454,000,000.00	1,318,000,000	1,082,000,000