Consolidated Statement of Shareholders' Equity (USD $) In Millions, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income	Deferred Equity Compensation
Balance at Dec. 31, 2012	$ 4,994	$ 2	$ 2,724	$ 1,749	$ 515	$ 4
Balance (in shares) at Dec. 31, 2012		194,003,297
Increase (Decrease) in Shareholders' Equity
Net income (loss)	459	0	0	459	0	0
Dividends ($0.30 per share)	(57)	0	0	(57)	0	0
Common stock repurchases (in shares)		(12,221,621)
Common stock repurchases	(259.0)	0	(259.0)	0	0	0
Share-based compensation and other (in shares)		426,789
Share-based compensation and other	6	0	6	0	0	0
Other comprehensive loss	(309)	0	0	0	(309)	0
Balance at Sep. 30, 2013	4,834	2	2,471	2,151	206	4
Balance (in shares) at Sep. 30, 2013		182,208,465
Balance at Jun. 30, 2013
Increase (Decrease) in Shareholders' Equity
Net income (loss)	384
Other comprehensive loss	(3)				(3)
Balance at Sep. 30, 2013	$ 4,834				$ 206