Derivative Financial Instruments (Details 5) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 entity	Dec. 31, 2013
Derivative Financial Instruments
Term of credit default swaps (in years)	5 years
Credit Derivatives
Notional amount	$ 11,219	$ 12,409
The number of reference entities generally included in a CDX index	125
Credit default swaps
Credit Derivatives
Notional amount	185	185
Fair value	(10)	(13)
Credit default swaps | Single name | Corporate debt
Credit Derivatives
Notional amount	5	5
Credit default swaps | First-to-default Basket | Municipal
Credit Derivatives
Notional amount	100	100
Fair value	(12)	(15)
Credit default swaps | Index | Corporate debt
Credit Derivatives
Notional amount	80	80
Fair value	2	2
AA | Credit default swaps
Credit Derivatives
Notional amount	1	1
AA | Credit default swaps | Index | Corporate debt
Credit Derivatives
Notional amount	1	1
A | Credit default swaps
Credit Derivatives
Notional amount	125	125
A | Credit default swaps | Single name | Corporate debt
Credit Derivatives
Notional amount	5	5
A | Credit default swaps | First-to-default Basket | Municipal
Credit Derivatives
Notional amount	100	100
A | Credit default swaps | Index | Corporate debt
Credit Derivatives
Notional amount	20	20
BBB | Credit default swaps
Credit Derivatives
Notional amount	55	55
BBB | Credit default swaps | Index | Corporate debt
Credit Derivatives
Notional amount	55	55
BB and lower | Credit default swaps
Credit Derivatives
Notional amount	4	4
BB and lower | Credit default swaps | Index | Corporate debt
Credit Derivatives
Notional amount	$ 4	$ 4