Consolidated Statement of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net Income (Loss) Attributable to Parent [Abstract]
Net income (loss)	$ (33)	$ 269	$ 218	$ 471
Other comprehensive income (loss):
Unrealized gain (loss) on investments, net of tax	0	(2)	2	2
Other comprehensive income (loss), net of tax	0	(2)	2	2
Comprehensive income (loss)	$ (33)	$ 267	$ 220	$ 473