Derivatives and Hedging Activities (Impact of Hedging Activity) (Details 5) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flow hedges [Member]
Derivative Instruments, Gain (Loss)
Estimated reclassification of net pretax losses on cash flow hedges from accumulated other comprehensive income to earnings during the next 12 months	$ 2
Cash flow hedge gain to be reclassified within twelve months to interest and debt expense	4
Cash flow hedge loss to be reclassified within twelve months recorded in net investment income	6
Amount of gain (loss) reclassified from accumulated other comprehensive income into income	0	0
Longest period of time over which the entity hedges exposure to the variability in future cash flows	21 years
Cash flow hedges [Member] | Interest and debt expense [Member]
Derivative Instruments, Gain (Loss)
Amount of gain (loss) reclassified from accumulated other comprehensive income into income	1	1
Cash flow hedges [Member] | Net investment income [Member]
Derivative Instruments, Gain (Loss)
Amount of gain (loss) reclassified from accumulated other comprehensive income into income	(1)	(1)
Fair value hedges [Member]
Derivative Instruments, Gain (Loss)
Number of interest rate swaps held	3
Fair value hedges [Member] | Fixed rate debt [Member] | Interest and debt expense [Member]
Derivative Instruments, Gain (Loss)
Amount of gain recognized in income on derivatives	$ 8	$ 8