Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net loss arising during the period, income tax expense (benefit)	$ (2)	$ (2)
Amortization of net loss included in net income, income tax expense (benefit)	1	1	5	3
Unrealized holding gain (loss) arising during the period, income tax expense (benefit)	(19)	(9)	(2)	(5)
Reclassification adjustments included in net income, income tax benefit	$ (6)	$ (6)	$ (13)	$ (12)