Investments (Analysis of Past Due Commercial Mortgage and Other Loans) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Current	$ 35,550	$ 31,772
30-59 Days Past Due	40	174
60-89 Days Past Due	19	28
Greater than 90 Days - Accruing	1	0
Greater than 90 Days - Not Accruing	188	432
Total Past Due	248	634
Total Financing Receivables	35,798	32,406
Commercial Loan on Hospitality [Member]
Current	1,486	1,467
30-59 Days Past Due	0	11
60-89 Days Past Due	0	10
Greater than 90 Days - Accruing	0	0
Greater than 90 Days - Not Accruing	0	96
Total Past Due	0	117
Total Financing Receivables	1,486	1,584
Commercial Mortgage Loan [Member]
Current	30,060	27,392
30-59 Days Past Due	18	154
60-89 Days Past Due	12	25
Greater than 90 Days - Accruing	0	0
Greater than 90 Days - Not Accruing	129	360
Total Past Due	159	539
Total Financing Receivables	30,219	27,931
Commercial Loan On Industrial Properties [Member]
Current	7,047	6,576
30-59 Days Past Due	0	0
60-89 Days Past Due	2	0
Greater than 90 Days - Accruing	0	0
Greater than 90 Days - Not Accruing	0	0
Total Past Due	2	0
Total Financing Receivables	7,049	6,576
Commercial Loan on Retail [Member]
Current	7,294	6,298
30-59 Days Past Due	0	71
60-89 Days Past Due	0	0
Greater than 90 Days - Accruing	0	0
Greater than 90 Days - Not Accruing	15	19
Total Past Due	15	90
Total Financing Receivables	7,309	6,388
Commercial Loan on Office [Member]
Current	6,369	5,774
30-59 Days Past Due	5	22
60-89 Days Past Due	0	0
Greater than 90 Days - Accruing	0	0
Greater than 90 Days - Not Accruing	17	7
Total Past Due	22	29
Total Financing Receivables	6,391	5,803
Commercial Loan On Apartment And Multi Family [Member]
Current	5,207	4,907
30-59 Days Past Due	0	33
60-89 Days Past Due	0	15
Greater than 90 Days - Accruing	0	0
Greater than 90 Days - Not Accruing	70	185
Total Past Due	70	233
Total Financing Receivables	5,277	5,140
Commercial Loan on Other [Member]
Current	2,657	2,370
30-59 Days Past Due	13	17
60-89 Days Past Due	10	0
Greater than 90 Days - Accruing	0	0
Greater than 90 Days - Not Accruing	27	53
Total Past Due	50	70
Total Financing Receivables	2,707	2,440
Agricultural Loan [Member]
Current	2,005	1,853
30-59 Days Past Due	0	1
60-89 Days Past Due	1	0
Greater than 90 Days - Accruing	1	0
Greater than 90 Days - Not Accruing	39	39
Total Past Due	41	40
Total Financing Receivables	2,046	1,893
Residential Property Loan [Member]
Current	988	847
30-59 Days Past Due	22	19
60-89 Days Past Due	6	3
Greater than 90 Days - Accruing	0	0
Greater than 90 Days - Not Accruing	18	22
Total Past Due	46	44
Total Financing Receivables	1,034	891
Other Collateralized Loans [Member]
Current	174	212
30-59 Days Past Due	0	0
60-89 Days Past Due	0	0
Greater than 90 Days - Accruing	0	0
Greater than 90 Days - Not Accruing	2	11
Total Past Due	2	11
Total Financing Receivables	176	223
Uncollateralized Loans [Member]
Current	2,323	1,468
30-59 Days Past Due	0	0
60-89 Days Past Due	0	0
Greater than 90 Days - Accruing	0	0
Greater than 90 Days - Not Accruing	0	0
Total Past Due	0	0
Total Financing Receivables	$ 2,323	$ 1,468