Derivatives and Hedging Activities (Details 5) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Derivative Instruments Gain (Loss)
Number of interest rate swaps held	3		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			4
Reclassification of net pretax losses, to be recorded in net investment income in the next 12 months			5
Amount of Gain (Loss) Reclassified from Accumulated other Comprehensive Income into Income				2
Hedging exposure to the variability in future cash flows			22 years
Cash flow hedges | Net investment income
Derivative Instruments Gain (Loss)
Amount of Gain (Loss) Reclassified from Accumulated other Comprehensive Income into Income	(1)	(1)	(2)	(3)
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	2	2
Cash flow hedges | Interest on debt
Derivative Instruments Gain (Loss)
Amount of Gain (Loss) Recognized in Other Comprehensive Income (Loss) 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	$ 10	$ 20	$ 19