Consolidated Statements of Shareholders' Equity (unaudited) - USD ($) $ in Millions	Total	Common Stock	Additional Paid in Capital	Accumulated Other Comprehensive Loss	Treasury Stock at Cost	Retained Earnings
Balance at Beginning of Period at Dec. 31, 2013	$ 9,184	$ 4	$ 3,463	$ (117)	$ (659)	$ 6,493
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	811	0	0	0	0	811
Stock-based Compensation	67	0	67	0	0	0
Exercise of Stock Options	45	0	45	0	0	0
Dividends	(182)	0	0	0	0	(182)
Changes in Treasury Stock, Net	(15)	0	0	0	(15)	0
Tax Benefits Related to Exercise of Stock Options	18	0	18	0	0	0
Net Change in Pension and Other	10	0	0	10	0	0
Balance at End of Period at Sep. 30, 2014	9,938	4	3,593	(107)	(674)	7,122
Balance at Beginning of Period at Dec. 31, 2014	10,325	4	3,624	(90)	(671)	7,458
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	(413)	0	0	0	0	(413)
Rosetta Merger	1,529	1	1,528	0	0	0
Stock-based Compensation	69	0	69	0	0	0
Exercise of Stock Options	7	0	7	0	0	0
Dividends	(214)	0	0	0	0	(214)
Changes in Treasury Stock, Net	(20)	0	0	0	(20)	0
Tax Benefits Related to Exercise of Stock Options	2	0	2	0	0	0
Issuance of Shares of Common Stock to Public, Net of Offering Costs	1,112	0	1,112	0	0	0
Net Change in Pension and Other	53	0	0	53	0	0
Balance at End of Period at Sep. 30, 2015	$ 12,450	$ 5	$ 6,342	$ (37)	$ (691)	$ 6,831