Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Schedule of Capitalization, Equity [Line Items]
Common stock, shares authorized	2,000,000,000		2,000,000,000		1,500,000,000
Common stock, par value (usd per share)	$ 0.01		$ 0.01		$ 0.01
NET INCOME (LOSS)	$ 495	$ (1,776)	$ 636	$ (2,844)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Schedule of Capitalization, Equity [Line Items]
NET INCOME (LOSS)	$ (7)	$ (10)	$ (17)	$ (14)
5.0% Cumulative Convertible Preferred Stock Series 2005 B [Member]
Schedule of Capitalization, Equity [Line Items]
Preferred Stock, Dividend Rate, Percentage			5.00%
4.50% Cumulative Convertible Preferred Stock [Member]
Schedule of Capitalization, Equity [Line Items]
Preferred Stock, Dividend Rate, Percentage			4.50%
5.75% Cumulative Convertible Preferred Stock [Member]
Schedule of Capitalization, Equity [Line Items]
Preferred Stock, Dividend Rate, Percentage			5.75%