Derivative Financial Instruments (Details 5) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014 entity	Dec. 31, 2013
Derivative Financial Instruments
Term of credit default swaps (in years)	5 years
The number of reference entities generally included in a CDX index	125
Credit Derivatives
Notional amount	$ 5,542	$ 14,003
Credit default swaps
Credit Derivatives
Notional amount	285	290
Fair value	(4)	(11)
Credit default swaps | Single name | Corporate debt
Credit Derivatives
Notional amount	105	110
Fair value	2	2
Credit default swaps | First-to-default basket | Municipal
Credit Derivatives
Notional amount	100	100
Fair value	(8)	(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	21	21
AA | Credit default swaps | Single name | Corporate debt
Credit Derivatives
Notional amount	20	20
AA | Credit default swaps | Index | Corporate debt
Credit Derivatives
Notional amount	1	1
A | Credit default swaps
Credit Derivatives
Notional amount	141	145
A | Credit default swaps | Single name | Corporate debt
Credit Derivatives
Notional amount	20	25
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	21	20
BBB | Credit default swaps
Credit Derivatives
Notional amount	118	120
BBB | Credit default swaps | Single name | Corporate debt
Credit Derivatives
Notional amount	65	65
BBB | Credit default swaps | Index | Corporate debt
Credit Derivatives
Notional amount	53	55
BB and lower | Credit default swaps
Credit Derivatives
Notional amount	5	4
BB and lower | Credit default swaps | Index | Corporate debt
Credit Derivatives
Notional amount	$ 5	$ 4