Contracts Accounted for as Credit Derivatives - Effect of Changes in Credit Spread (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Credit Risk Derivatives, 100 Percent Widening in Spreads, Effect on Fair Value	[1]	$ (791)
Credit Risk Derivatives, 50 Percent Widening in Spreads, Effect on Fair Value	[1]	(590)
Credit Risk Derivatives, 25 Percent Widening in Spreads, Effect on Fair Value	[1]	(490)
Credit Risk Derivatives, 10 Percent Widening in Spreads, Effect on Fair Value	[1]	(430)
Fair value of credit derivative asset (liability), net		(389)	[1]	$ (365)
Credit Risk Derivatives, 10 Percent Narrowing in Spreads, Effect on Fair Value	[1]	(351)
Credit Risk Derivatives, 25 Percent Narrowing in Spreads, Effect on Fair Value	[1]	(295)
Credit Risk Derivatives, 50 Percent Narrowing in Spreads, Effect on Fair Value	[1]	(203)
Credit Risk Derivatives, 100 Percent Widening in Spreads, Effect on Unrealized Gain (Loss)	[1]	(402)
Credit Risk Derivatives, 50 Percent Widening in Spreads, Effect on Unrealized Gain (Loss)	[1]	(201)
Credit Risk Derivatives, 25 Percent Widening in Spreads, Effect on Unrealized Gain (Loss)	[1]	(101)
Credit Risk Derivatives, 10 Percent Widening in Spreads, Effect on Unrealized Gain (Loss)	[1]	(41)
Credit Risk Derivatives, Base Scenario, Effect on Unrealized Gain (Loss)	[1]	0
Credit Risk Derivatives, 10 Percent Narrowing in Spreads, Effect on Unrealized Gain (Loss)	[1]	38
Credit Risk Derivatives, 25 Percent Narrowing in Spreads, Effect on Unrealized Gain (Loss)	[1]	94
Credit Risk Derivatives, 50 Percent Narrowing in Spreads, Effect on Unrealized Gain (Loss)	[1]	$ 186

[1] Includes the effects of spreads on both the underlying asset classes and the Company’s own credit spread.