Derivatives and Hedging Activities (Details 5) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Derivative Instruments Gain (Loss)
Number of interest rate swaps held	3
Cash flow hedges
Derivative Instruments Gain (Loss)
Cash flow hedge, Gain (Loss) Reclassified from Accumulated Other Comprehensive Income to Other revenues		$ 3
Estimated reclassification of net pretax losses on cash flow hedges from accumulated other comprehensive income to earnings during the next 12 months	1
Reclassification of net pretax gains, to be recorded as a reduction to interest and debt expense in the next 12 months	5
Reclassification of net pretax losses, to be recorded in net investment income in the next 12 months	6
Amount of Gain (Loss) Reclassified from Accumulated other Comprehensive Income into Income		2
Hedging exposure to the variability in future cash flows	23 years
Cash flow hedges | Net investment income
Derivative Instruments Gain (Loss)
Amount of Gain (Loss) Reclassified from Accumulated other Comprehensive Income into Income	(1)	(2)
Cash flow hedges | Other revenues
Derivative Instruments Gain (Loss)
Amount of Gain (Loss) Reclassified from Accumulated other Comprehensive Income into Income		3
Cash flow hedges | Interest and debt expense
Derivative Instruments Gain (Loss)
Amount of Gain (Loss) Reclassified from Accumulated other Comprehensive Income into Income	1	1
Cash flow hedges | Interest on debt
Derivative Instruments Gain (Loss)
Amount of Gain (Loss) Recognized in Other Comprehensive Income on Derivatives		14
Fair value hedges | Fixed rate debt | Interest and debt expense
Derivative Instruments Gain (Loss)
Amount of Gain Recognized in Income on Derivatives	$ 10	$ 9