Consolidated Statement of Comprehensive Income (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net Income (Loss) Attributable to Parent [Abstract]
Net income (loss)	$ 900	$ 147	$ (1,184)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	0		3
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax, Including OTTI		7
Other comprehensive income (loss):
Other Comprehensive Income (Loss), Net of Tax	(3)	9	3
Unrealized gain (loss) on post-retirement benefits, net of tax	(3)	2	0
Comprehensive income (loss)	$ 897	$ 156	$ (1,181)