Quarterly Financial and Market Information (Unaudited) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial and Market Information
Net revenues	$ 1,518	$ 691	$ 1,050	$ 1,324	$ 1,768	$ 841	$ 1,075	$ 1,172	$ 4,583	$ 4,856	$ 4,755
Cost of sales	655	175	285	416	682	237	377	364
Operating (loss) income	284	70	430	587	484	227	227	513	1,372	1,451	1,328
Net income	$ 174	$ 56	$ 324	$ 456	$ 354	$ 226	$ 185	$ 384	$ 1,010	$ 1,149	$ 1,085
Basic earnings per common share (in dollars per share)	$ 0.23	$ 0.05	$ 0.28	$ 0.40	$ 0.31	$ 0.20	$ 0.16	$ 0.34	$ 0.96	$ 1.01	$ 0.93
Diluted earnings per common share (in dollars per share)	$ 0.22	$ 0.05	$ 0.28	$ 0.40	$ 0.31	$ 0.20	$ 0.16	$ 0.33	$ 0.95	$ 1.01	$ 0.92