Investments and Derivative Instruments Level 4 Cash Flow Hedges (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivatives in Cash Flow Hedging Relationships [Abstract]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 54,000,000
Maximum Term Over for Hedging Exposure to Variability of Future Cash Flows	3 years
Cash Flow Hedging [Member]
Derivatives in Cash Flow Hedging Relationships [Abstract]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	$ 28,000,000	$ 140,000,000	$ (303,000,000)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	2,000,000	(3,000,000)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	59,000,000	73,000,000	192,000,000
Interest Rate Swap [Member] | Cash Flow Hedging [Member]
Derivatives in Cash Flow Hedging Relationships [Abstract]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	28,000,000	150,000,000	(315,000,000)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net		2,000,000	(3,000,000)
Currency Swap [Member] | Cash Flow Hedging [Member]
Derivatives in Cash Flow Hedging Relationships [Abstract]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net		(10,000,000)	12,000,000
Accumulated Other Comprehensive Income (Loss) [Member]
Derivatives in Cash Flow Hedging Relationships [Abstract]
Loss on Discontinuation of Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring	$ 0	$ 0	$ 0