Short-Term and Long-Term Debt (Schedule of Extinguishment of Debt) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Details underlying the recognition of gain or loss on extinguishment of debt [Abstract]
Gain (loss) on extinguishment of debt, pre-tax	$ (5)	$ (8)	$ (5)
Junior subordinated debentures [Member]
Details underlying the recognition of gain or loss on extinguishment of debt [Abstract]
Principal balance outstanding prior to payoff			(155)
Unamortized debt issuance costs and discounts prior to payoff			5
Amount paid to retire			155
Gain (loss) on extinguishment of debt, pre-tax			(5)
Capital securities [Member]
Details underlying the recognition of gain or loss on extinguishment of debt [Abstract]
Principal balance outstanding prior to payoff		(275)
Unamortized debt issuance costs and discounts prior to payoff		8
Amount paid to retire		275
Gain (loss) on extinguishment of debt, pre-tax		(8)
Senior notes [Member]
Details underlying the recognition of gain or loss on extinguishment of debt [Abstract]
Principal balance outstanding prior to payoff	(15)
Unamortized debt issuance costs and discounts prior to payoff	0
Amount paid to retire	20
Gain (loss) on extinguishment of debt, pre-tax	$ (5)