Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid in Capital	Accumulated Other Comprehensive Loss	Treasury Stock at Cost	Retained Earnings	Non-controlling Interests
Shareholders Equity, Beginning Balance at Dec. 31, 2014	$ 10,325	$ 4	$ 3,624	$ (90)	$ (671)	$ 7,458	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss) Income	(2,441)					(2,441)
Merger and Acquisition	1,529	1	1,528
Stock-based Compensation	86		86
Exercise of Stock Options	8		8
Dividends	(291)					(291)
Issuance of Stock, Net of Offering Costs	1,112		1,112
Net Change in Other	42		2	57	(17)
Shareholders Equity, Ending Balance at Dec. 31, 2015	10,370	5	6,360	(33)	(688)	4,726	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss) Income	(985)					(998)	13
Stock-based Compensation	68		68
Exercise of Stock Options	24		24
Dividends	(172)					(172)
Issuance of Stock, Net of Offering Costs	299						299
Net Change in Other	(4)		(2)	2	(4)
Shareholders Equity, Ending Balance at Dec. 31, 2016	9,600	5	6,450	(31)	(692)	3,556	312
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (Loss) Income	(1,050)					(1,118)	68
Merger and Acquisition	1,851		1,876		(25)
Stock-based Compensation	100		100
Exercise of Stock Options	10		10
Dividends	(190)					(190)
Issuance of Stock, Net of Offering Costs	312						312
Distributions to Noncontrolling Interest Owners	(28)						(28)
Net Change in Other	14		2	1	(8)		19
Shareholders Equity, Ending Balance at Dec. 31, 2017	$ 10,619	$ 5	$ 8,438	$ (30)	$ (725)	$ 2,248	$ 683