Investments (Details 34) (USD $) In Millions, unless otherwise specified	Sep. 30, 2011	Dec. 31, 2010
Agricultural Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	$ 12,967	$ 12,751
% of Total	100.00%	100.00%
Residential Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	3,424	2,231
% of Total	100.00%	100.00%
Less than 65% [Member]
Agricultural Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	11,818	11,483
% of Total	91.10%	90.10%
65% to 75% [Member]
Agricultural Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	740	885
% of Total	5.70%	6.90%
76% to 80% [Member]
Agricultural Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	19	48
% of Total	0.20%	0.40%
Greater than 80% [Member]
Agricultural Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	390	335
% of Total	3.00%	2.60%
Performing [Member]
Residential Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	3,399	2,149
% of Total	99.30%	96.30%
Nonperforming [Member]
Residential Mortgage Loans - by Credit Quality Indicator:
Recorded investment in Mortgage Loan	$ 25	$ 82
% of Total	0.70%	3.70%