Investments and Derivative Instruments (Details 13) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Macro hedge program
Notional Amount	$ 151,155	$ 141,436
Fair Value	(1,045)	(458)
International [Member]
Macro hedge program
Notional Amount	37,200	32,300
Macro Hedge Program [Member] | U.S. [Member]
Macro hedge program
Notional Amount	5,458	6,819
Fair Value	173	357
Macro Hedge Program [Member] | International [Member]
Macro hedge program
Notional Amount	45,215	33,726
Fair Value	201	750
Currency Forwards [Member] | Macro Hedge Program [Member] | International [Member]
Macro hedge program
Notional Amount	12,713	8,622
Fair Value	(105)	446
Currency options [Member] | Macro Hedge Program [Member] | International [Member]
Macro hedge program
Notional Amount	10,135	7,357
Fair Value	83	127
Equity futures [Member] | Macro Hedge Program [Member] | U.S. [Member]
Macro hedge program
Notional Amount	0	59
Fair Value	0
Equity futures [Member] | Macro Hedge Program [Member] | International [Member]
Macro hedge program
Notional Amount	2,784	3,835
Fair Value	0
Equity options [Member] | Macro Hedge Program [Member] | U.S. [Member]
Macro hedge program
Notional Amount	5,458	6,760
Fair Value	173	357
Equity options [Member] | Macro Hedge Program [Member] | International [Member]
Macro hedge program
Notional Amount	2,872	1,565
Fair Value	142	74
Equity swaps [Member] | Macro Hedge Program [Member] | International [Member]
Macro hedge program
Notional Amount	1,287	392
Fair Value	4	(8)
Interest rate futures [Member] | Macro Hedge Program [Member] | International [Member]
Macro hedge program
Notional Amount	531	739
Fair Value	0
Interest Rate Swaps and Swaptions [Member] | Macro Hedge Program [Member] | International [Member]
Macro hedge program
Notional Amount	14,893	11,216
Fair Value	$ 77	$ 111