Derivative Instruments (Balance Sheet Offsetting) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financial Assets
Derivative Instruments, Gross amount of recognized assets	$ 1,917	$ 1,805
Derivative Instruments, Gross amounts offset	(775)	(924)
Derivative Instruments, Net amount of assets	1,142	881
Derivative Instruments, Cash collateral	(1,063)	(623)
Derivative Instruments, Net amount	79	258
Embedded Derivative Instruments, Gross amount of recognized assets	932	1,244
Embedded Derivative Instruments, Gross amounts offset
Embedded Derivative Instruments, Net amount of assets	932	1,244
Embedded Derivative Instruments, Cash collateral
Embedded Derivative Instruments, Net amount	932	1,244
Total, Gross amount of recognized assets	2,849	3,049
Total, Gross amounts offset	(775)	(924)
Total, Net amount of assets	2,074	2,125
Total, Cash collateral	(1,063)	(623)
Total, Net amount	1,011	1,502
Financial Liabilities
Derivative Instruments, Gross amount of recognized liabilities	161	242
Derivative Instruments, Gross amounts offset	(95)	(55)
Derivative Instruments, Net amount of liabilities	66	187
Derivative Instruments, Cash collateral	(63)
Derivative Instruments, Net amount	3	187
Embedded Derivative Instruments, Gross amount of recognized liabilities	1,376	1,156
Embedded Derivative Instruments, Gross amounts offset
Embedded Derivative Instruments, Net amount of liabilities	1,376	1,156
Embedded Derivative Instruments, Cash collateral
Embedded Derivative Instruments, Net amount	1,376	1,156
Total, Gross amount of recognized liabilities	1,537	1,398
Total, Gross amounts offset	(95)	(55)
Total, Net amount of liabilities	1,442	1,343
Total, Cash collateral	(63)
Total, Net amount	$ 1,379	$ 1,343