Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at December 31,	$ 11,397
OCI before reclassifications, net of income tax	(811)
Amounts reclassified from AOCI, net of income tax	(6)
Balance at March 31,	10,580
Unrealized Investment Gains (Losses) Net of Related Offsets [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at December 31,	13,590
OCI before reclassifications, net of income tax	(99)
Amounts reclassified from AOCI, net of income tax	(159)
Balance at March 31,	13,332
Unrealized Gains (Losses) on Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at December 31,	829
OCI before reclassifications, net of income tax	(40)
Amounts reclassified from AOCI, net of income tax	116
Balance at March 31,	905
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at December 31,	(533)
OCI before reclassifications, net of income tax	(672)
Amounts reclassified from AOCI, net of income tax	0
Balance at March 31,	(1,205)
Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at December 31,	(2,489)
OCI before reclassifications, net of income tax	0
Amounts reclassified from AOCI, net of income tax	37
Balance at March 31,	$ (2,452)